Sure, if you deny a basic premise of 4e's damage mechanics - that bleeding occurs when the "bloodied" state is incurred - then you won't like a mechanic that links having blood drip on you to having bloodied your enemy! But the answer to your question is no mystery - you answered it yourself!
OK, but all I find in the PHB about bloodied is that it is the point that you are at half hit points and some abilities may be triggered by it. I don't see anything that indicates that it actually describes what it means in the game world, although I seem to remember something along the lines that it is when you can visibly see that the creature is suffering, etc. The idea that being bloodied means that blood is spraying everywhere doesn't fit my concept of what combat looks like, particularly when all the damage has been bludgeoning, or psychic for example.
This is something that 4e leaves to GM adjudication. And, as [MENTION=87792]Neonchameleon[/MENTION] pointed out, by default most swords used by PCs to stab this dragon will be magic.
The GM is of course free to narrate that NPCs who tried to stab the dragon with non-magic swords had their swords corrode. That's just colour.
This is a fundamental change in the game, and forces a change in my world. In my world dragons occasionally attack civilized areas. And armies of non-magical weapon wielding people could possibly kill a dragon, however unlikely. Again, one of the specific things that I consider a bad rule for our campaign. Plus a sword that is damaged and or broken is not color, it's a big deal if that's your only weapon.
Why does the dragon breathe when it starts bleeding? Because it's now really angry! It's a pacing mechanic - it helps express, at the table and in the course of resolution, the story of the dragon's anger.
As I stated, I get that this is what people tell me. But why is it restricted to only this action, and also that the rule now forces the fiction - now it's angry. What if it's worried and decides to launch into the air out of reach. Of course you'll say I have the option to do that, but I'll cover that in a moment...
Your question about the tail sits oddly with your preference for legendary actions, because they exhibit the same property: the dragon can only make a wing attack off turn; and the more enemies there are, the more attacks the dragon can make (and the more Perception checks it can make!). These are all mechanisms for managing pacing and action economy. They're are not mechanical representations of dragon biology.
I like legendary actions, I didn't say I always liked how they were implemented. In 4e the stat block lists triggers - that is something that presumably causes one of the listed actions automatically. Again, forcing my fiction. Legendary actions are extra actions that can be taken any time that the dragon desires, out of turn. That's a much more elegant solution to me.
The specific approach, such as adding abilities like a tail sweep that isn't a possible part of its regular action doesn't make much sense. But the framework is there, and again, I like the framework of legendary actions better than triggers.
(I'll bracket the issue of Action Recovery, which is standard in MV dragons.)
It's not a "limitation" - it's about providing a particular experience at the table. The game tends to assume that a fight with a dragon will be a fairly big deal, and that there won't be a lot of repeats. The abilities are intended to help each of those fights to have a distinctive, memorable feel. So it's a mistake to infer from the allocation of abilities to some sort of conjecture about "dragon biology".
Any dragon can fly and attack. But creatures with a fly-by attack ability will be particularly noteworthy for their flying by and attacking. That will be part of the experience of fighting them.
Within the context of 4e this questio makes no sense. Hit points aren't a property of ogres (like their height, weight, or hair colour). They're an element of monster stat blocks, and serve as a marker for the degree of staying power this creature has in combat.
So the GM (i) has to decide what degree of staying power a creature should have; and the (ii) has to assign hit points. 4e has fairly intricate advice on how to move from (i) to (ii), based on its hp/level charts and its categories of standard, elite, solo, etc. The decison at (i), though, can be decided either by accepting the default suggestions (by working from the MM) or by making one's own decision about pacing, genre considerations, etc.
Once again, a fundamental change in the way the game works. This is one of the biggest ones that predicated bounded accuracy. Because a bear is a bear is a bear. Sure you can have a juvenile bear, or an adult, or even an elderly bear. There will be some variation between one individual and another. But for a bear to be scaled up simply to be a reasonably balanced encounter for high-level PCs, is now capable of wandering through the village and causing the damage to said village of a small giant.
As Neonchameleon explained, in 4e if you don't want your black dragon to be an instinctive devourer, then you change the statblock. The game is predicated on the idea that the function of the mechanics is to produce the desired experience in play, including the desired fiction. If you want different fiction, you change the mechanics!
For instance, the only time I used a black dragon in 4e was a young one using the MM (not the MV stats). [MENTION=87792]Neonchameleon[/MENTION] described it as anaemic, but for me it worked well, and it's darkness ability generated the sort of play experience I wsa hoping for. Likewise I've had good play experiences with wraiths (a monster many people hate because they are insubstantial - half damage - and cause weakness - more half damage).
But if I wanted a different play experience, I would change things. I do this all the time in 4e - change stat blocks to help ensure that the creature, in play, will be as I envisage it and want it to be in the fiction.
That's why it makes no sense, in the 4e context, to ask "Why are black dragons like this?"; or to conjecture about how many hit points an ogre "ought" to have. The stats are intended as a producer of the fiction; not as a product or record or model of it. If you want different fiction, you change the stats! It's fiction first, mechanics second. (Which I think is fairly close to how Chainmail and OD&D were designed, but different from later AD&D and very different from 3E.)
I'll start with it's intended as a producer of the fiction. I have stated repeatedly that's exactly what I
don't want. I want the rules to adjudicate the fiction, not create it.
You also state "if you want different fiction, you change the mechanics." Something that I also disagree with, the
mechanics of the game should remain consistent no matter what. Yes, I advocate altering the mechanics with house rules so the mechanics meet your needs. But after that, they remain the same. Altering stats of a monster is not altering mechanics. It's altering the abilities of the creature.
Your stated approach is the fiction (which I would consider a description of what the creature is - how it looks, how it acts, how it fits the world, etc.) and mechanics second. In the context of the abilities of a monster I think rather than mechanics, statistics is more appropriate.
So your stated approach is the envision what you want the dragon to be like, then select the abilities. This appears to be a direct contradiction of the design advice given in the DMG (see below) where the "what the creature is like" is the last step of the process, after you've determined all of its combat-oriented abilities.
So altering monsters to suit your needs or tastes is not edition specific. You state that 4e is designed to only tell you about the combat info in the stat blocks, leaving the rest to the DM. For any other edition (and really 4e) the assumption and design intent is that everything you need is in the core books. If you want to design your own campaign, modify monsters, etc. that's fine, and to a large degree encouraged. But you don't have to.
Here's what the DMG has to say about it:
"The Monster Manual provides hundreds of enemies for your adventures, but they aren’t all that’s available. You can customize existing monsters to increase their utility, making them stronger, weaker, or just different. Whether you want to bump an ogre up a few levels or turn it into an elite berserker, this section gives you the tools you need to tinker with monsters. You’ll also find rules for adding a class to a monster, mining the Player’s Handbook for combat powers. You can use several methods to adjust an existing monster: change its level, give it equipment, alter its appearance and behavior, and apply a template. Each of these approaches is discussed below."
In the entire chapter, this is what it says about non-combat stuff:
"Cosmetic Changes
The characters are delving into the jungle-covered ruins of an ancient city now haunted by the yuan-ti. There they discover strange arboreal humanoids with long arms that swoop into battle on the backs of giant wasps. What are these mysterious beings? This technique is useful for keeping players on their toes even when they know the Monster Manual backward and forward. Use the statistics of a given monster but completely alter its appearance when you describe it to the players. You can make minor changes to its powers as well, altering damage types or changing details of weapons (lashing tentacles become a whipping tail, for example)."
Under "Designing Monsters" it would appear to me that the intended design process is "mechanics (stats) first, fiction second":
"Following these steps won’t result in a fully designed and developed monster, but they’ll provide a good approximation.
1. Choose Level. The level of the monster determines its key statistics, including defenses, attack bonuses, and hit points.
2. Choose Role. A monster’s role suggests the kinds of powers it uses in combat. Chapter 4 describes monster roles more fully, and the Monster Statistics by Role table on this page shows how a monster’s role influences the statistics and powers you give it.
3. Determine Ability Scores. It’s helpful to think of ability scores in pairs, each pair corresponding to one of the three defenses (Fortitude, Reflex, and Will). Ability scores also help determine the monster’s attack bonuses, ability and skill checks, and Armor Class. On average, the highest ability score of a pair is equal to 13 + one-half the monster’s level. For example, the target score for an 8th-level monster is 17 (13 + 4). However, set the ability that governs the monster’s primary attacks to be 3 higher, or 16 + one-half the monster’s level. An 8th-level monster that relies on melee attacks should have a Strength of 20.
4. Determine Hit Points. Level and role determine hit points. The monster gains a flat number of hit points at each level, just as characters do. Use the Monster Statistics by Role table to set hit points.
5. Calculate Armor Class. A monster’s Armor Class is based on its level and role. Average AC is equal to 14 + the monster’s level, but some roles alter this target number, as shown in the table.
6. Calculate Other Defenses. A monster’s level determines its defenses. A given defense based on an average ability score is equal to 12 + the monster’s level. For every 2 points the ability score varies from the average, adjust the defense by +1 (if higher) or –1 (if lower).
7. Choose Powers. The most complex part of monster creation is creating powers for the monster. For inspiration, check the powers for creatures in the Monster Manual. That book has a list of monsters by level and role, so you can quickly look up other creatures that are similar to your new monster. Then either choose some powers that seem right, modifying them as needed, or create new ones of comparable effect. A monster needs a basic attack, which can be melee or ranged and is usable at will; some kinds of monsters might have a second basic attack. Then add one encounter power or rechargeable power per tier (one at heroic, two at paragon, three at epic).
8. Calculate Attack Bonus. The monster’s attack bonus is a function of its level and role. Powers that target AC typically have a higher attack bonus than those that target other defenses.
9. Set Damage for Attacks: Use the Damage by Level table to set damage for the monster’s attacks. Most at-will attacks should use the medium normal damage shown on the table. For attacks against multiple targets, the melee attacks of artillery monsters, and controller attacks that also include significant control functions, use the low normal damage column. For attacks that have low accuracy (including brute attacks) and the high-damage attacks of lurker monsters, use the high normal damage column. Use the limited damage expressions for powers the monster can use only once or twice a fight—powers that have encounter recharge or recharge rolls.
10. Additional Details. Monster design doesn’t stop once you’ve done all the math. Add flavor, appearance, and tactics to round out your creation."
This process starts with aspects that don't define the creature at all. In other words it's basically saying: I need a level 5 creature that is a brute, and needs to be strong, you calculate hit points and AC (which is based on armor and role, so at this stage it could be an animated cotton ball or an animated rock and still have the same AC because it apparently has nothing to do with what the creature is, or its natural defenses, etc.), add defenses, and then powers.
Now choosing powers probably requires some idea of what the heck you are attempting to create, but until this point it doesn't make any difference what the monster is, according to this design approach. Then we're back to attack bonuses and damage, which don't have anything to do with what it is again. We haven't defined the actual attacks yet, just the impact they'll have in combat.
Finally we get to step 10, where we actually decide what the heck it is. Presumably this will help define what the attacks are the have the bonus and damage determined in steps 8 and 9. This design process is entirely mechanics (or stats) first, then fiction. There is not a single instruction before this point that recommends that you decide what the monster is. And step 10 even acknowledges that the prior steps have been all math.
As a published game, somebody who has never played before should be able to pick up the books and play without being required to provide half of the details of the monsters. And that's generally how things will be played. An objection that [MENTION=87792]Neonchameleon[/MENTION] had about 3e stat blocks is that they cross referenced existing material. A common publishing method usually related more to economics of printing than a design decision. Yet then he and you infer that the MM in 4e only provides the combat stuff, and the rest isn't documented
anywhere. That doesn't make any sense to me.
So say you're not new to D&D, you're like me. Who is used to 3+ prior editions where the information in the MM is essentially complete (cross-reference or not). That includes things like ecology, numbers appearing, flavor text (and the trend back then was to cover the flavor text quite a bit, including spewing the "Ecology of" series of articles in Dragon magazine). What do I see in 4e design? Combat, combat, and more combat. The monster stats are all combat. The instructions for building a monster is 9 steps of building combat stats, then two sentences to "add flavor, appearance, and tactics to round out your creation."
The 10 steps of designing monsters presents what the designers feel is most important in designing a monster. Nine steps of combat oriented design is a pretty clear intent.
Compare to the 3.5e approach:
"The Monster's Concept
Before you begin assigning statistics and other particulars, take some time to think about the basic nature, or concept, of your monster.
Think of the following when working on your concept:
-What do you expect the creature to do in the game? (Is it a friend or foe of the PCs? Does it depend primarily on physical or mental abilities? Is it meant to be encountered once or on a recurring basis?
-Where does it live? (A monster that lives underground may have characteristics not shared by monsters that inhabit the wilderness and vice versa.)
-How does it live? (Is it a predator that relies on its own strength and speed, or is it intelligent enough to get other creatures to do its bidding?)
-Does it have any particular enemies or favorite prey?
After you have an idea of what your monster is about, you'll have a much easier time making your creature's type, ability scores, feats, skills, and special powers to fit your concept. It's okay to model your monster on a creature that's already in the game-you'll have less work to do and your monster will be easier to use. You'll find that a short menu of special abilities tightly wedded to your concept makes the best monster, and it makes the monster much easier to use."
2e approached it with guidance that covers combat and other options in a brief introduction, and then goes through the design process in the same order that things are presented in the stat block (which is not alphabetical, but seems to have been organized in an order that makes sense for use of the monster): Climate (where it notes that only tool-making creatures will be found in every climate); Frequency ("Most monsters avoid settled areas..."); Organization ("Give a lot of thought to this entry..."; Activity Cycle; Diet; Intelligence; Treasure; Alignment; No. Appearing; and then Combat statistics. It also includes appearance, habitat/society, and ecology entries among others. While stats like the habitat/society in particular are things that I think are best covered in specific settings, the point is that the monster design was more wholistic, not centered or focused on just combat. There aren't many guidelines here, but the approach is clearly different.
While combat abilities certainly enter the design process, this approach has a much broader look at the creature itself - where and how it lives, and typical enemies and prey. These are all pointing more to how it fits in the world than whether it will be "interesting in combat" to the players.
Perhaps I misread the intentions of 4e monsters and their design, particularly in the context of how the rules seem to be very combat oriented in general. But starting on the first monster of the 4e MM - an aboleth. What is it?
"ABOLETHS ARE HULKING AMPHIBIOUS CREATURES that hail from the Far Realm, a distant and unfathomable plane. They live in the Underdark, swimming through drowned crannies or creeping through lightless tunnels and leaving trails of slimy mucus in their wake. Malevolent and vile, aboleths bend humanoid creatures to their will, and more powerful aboleths can transform their minions into slimy horrors."
That's the extent of the description. Nothing else, not even what they look like (presumably the assumption is that the picture takes care of that). The aboleth lore section covers a tiny bit more. Otherwise it's nothing but stat blocks (which you say are designed primarily for combat use) and combat tactics.
Again, all I'm saying, is that I personally don't like the monster design approach in 4e. My perception is that the design process is reversed, focusing on combat first, putting more weight on things that make them interesting and or different in combat, and very little that concerns the world, and how the creatures fit within the world. It actually reminds me of early D&D approaches, where there are dungeons full of monsters in their rooms, without any consideration of how they get food, much less why natural enemies don't care that they are living just down the hall. Gygaxian ecology followed, then what I'll call Greenwood ecology, with the "Ecology of the..." series in Dragon (I think he as the original author of the first and many of those). Obviously, outside of D&D there were many other games that presented things in this context, ICE MERP/Rolemaster comes to mind.
I'm not debating the merits, whether one is better than the other. Nor am I debating what a creative DM
can do with the rules. Just my personal preference to the design approach.