CR-like Comparisons
I'm restricting myself to 3e and 4e, here, as those are the systems with which I have the most experience DMing. (I've played everything but OD&D, but only really DMed extensively in the latest two editions.)
TL;DR: 4e monsters potentially OHKO 4e PCs with the same (or greater) frequency than 3e monsters of the same "game usage" space do to 3e PCs. 3e monsters are far more vulnerable to being OHKOed by the PCs than are 4e monsters.
I think that "hit die" is a poor choice for comparison within the 3e/4e rules set. The better tool, in my opinion, is to look at how they are intended to be used, meaning by CR (3e) or level (4e).
[sblock="Rationale for CR and Level usage"]By definitions, we can look at CR 1/4 as being roughly equivalent to a level one monster. (Reasoning: Four CR 1/4 monsters create an "equal level" challenge for a party of four 3e characters; this is identical to the situation for a 4e party facing off against an equal number of level one monsters.) Similarly, a CR 1/2 monster is equal to either a level one elite or a level five standard monster. A full CR 1 monster would be roughly equal to a level one solo.
The closest thing to a level one minion is a CR 1/10 or so 3e critter. (It should be a CR 1/16 or so, but no such creatures exist, to my knowledge.) The CR 1/10, 1/8, and 1/6 will have to fill in for minions up to about level 8; a level 9 minion is 100 xp, the same as a level 1 standard monster, so CR 1/4.[/sblock]
What that means to me is that I can look at CR 1/4 stuff and compare it to standard level one monsters (no elites, solos, or minions).
[sblock="3e and 4e Damage Comparisons"]With that basis for comparison, only rogues and wizards are vulnerable to one-shot-KOs from CR 1/4 types. The highest damage I found for a single standard action used to attack was the kobold at 1d6-1. (The kobold zombie is listed in the table as CR 1/4, it is in the book as CR 1/2. It has a crossbow attack that does 1d6 damage.) In no case is a tougher class vulnerable. All the CR 1/4 types (except the ambiguous zombie kobold) have really tiny hit points, making them equally vulnerable to being taken out by single attacks from pretty much anyone.
In 4e, there are several standard monsters with damages that let them one-shot the same sort of lower-hit-point PCs that are vulnerable in 3e. Bullywug Muckers and Leapers can get to 24 damage (30 for the mucker if the PC is already prone), Lowtown Urchins get to 24, and topping things out, the Silt Runner Rager can hit for up to 33. (28 is the normal max, but that same hit gives vulnerable 5 to all damage. Though getting 33 damage does require a previous hit from the Rager, it is theoretically possible that the Rager hit, the target was healed to full, then the rager hit again, one-shotting the PC from full hit points -- this is obviously a corner case.)
The damages here of the bullywug and silt runner put even defenders without a con priority in serious danger. About a dozen level one standards can one-hit-KO those low-hit-point PCs. (This doesn't include ongoing damage, which can technically OHKO a target if its luck is bad enough ... ) Honorable mention goes to the Kobold quickblade, who deals 1d6+11 if used well, the goblin archer who deals 1d8+1d6+2, and the lesser air elemental who deals 2d6+4 plus grabs the target (while grabbed, the target takes ongoing 5, plus it takes half the damage from any ranged or melee attacks on the air elemental). Though unable to OHKO, these deal pretty decent damage, enough to scare relatively high hit point characters.
The real winner, then, is the durability of the 4e monsters. They seem to mostly have between 22 and 28 hit points (with outliers as low as 17 and as high as 38, I think). That puts them, unlike every one of the 3e CR 1/4 monsters, largely out of reach of PC at-will damages. (Everything is vulnerable to the right daily or even some encounter option, and most are easily within reach of the right sort of rogue with combat advantage sneak-attacking or other high-damage striker.)[/sblock]
In conclusion, a smallish subset of 4e level one standard monsters can one-shot a PC of low max hit points, and a couple (out of the 66 or so in the monster-builder) can even one-shot all but the toughest 4e PCs. They are only vulnerable to being one-shotted by damage-optimized PCs or through use of daily abilities (and maybe an odd encounter power or so from a semi-damage-optimized PC). A similarly small subset of the 3e CR 1/4 monsters (essentially equivalent to the above in game usage) can one-shot relatively low hit point characters, but none can one-shot a fighter-type. They are all within easy reach of being killed by one shot from pretty much any PC.
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To address the OP:
TrippyHippy said:
The big bugbear for me, however, largely boils down to to same core issue I have with D&D 4th edition (and Pathfinder actually). And that is the power creep.
Why do Hit Points have to be so high at 1st level - out of synch with all other NPC dwellers?
You are partly right, there. For at least four editions (1e-4e), the hit point values for PCs have been in the ballpark of the hit point values for monsters/NPCs. It is only in the 5e playtest where this isn't the case, and there is little reason to suspect that it will remain that way, as monsters are admittedly unfinished. (I object to the implication that PCs had more hit points than NPCs in 4e. That is largely false. What they do have is access to more in-combat healing and much more between-encounter healing. Where 4e PCs largely deviate from earlier-editions PCs' hit-point totals is when compared to base weapon damages. There, they are much more resilient. As seen above, though, this doesn't likely apply to actual attacks from many sources, be they PC or NPC.)
[sblock="The OP's Five Points, and Comments thereupon"]
1) Make the HD the sole measure of HP (with a Con modifier for each level). Have characters gain up to 10HD at 10th Level, then simply stop awarding them after that.
2) Give Fighters a d10 HD again. Actually, I'd arguably give them a D8, so that the HP are equitable with other characters and NPC Warriors). Levy their 'Feats' so that, at 1st level at least, combat is challenging. They can gain more dramatic feats as they progress, but it needs to be levied.
3) Make Wizards 'minor spells' actually minor in effect. Anything that directly causes damage, without needing to roll, is not a minor effect. Cantrips should be effects that gain useful little benefits, like opening doors or moving small objects around, but are not flashy evocations of power.
4) Make the skills the main focus of the Rogue Class - not just the 'striker' role (although, admittedly, this is much better in D&D Next than it was in 4th Ed). I'm not asking for big long lists (definitely not!), but what about being able to pickpocket again?
5) Be wary of escalating bonuses. Already, at 1st level the Fighter seems to have massive bonuses on damage and attacks - indeed, almost all the characters have bonuses of some type, and it's hard to track where some of them are coming from. Also, incidentally, are they going to go back to adding 1/2 Level to Skill checks and Attacks? It is not clear in the play test, although I actually wouldn't mind as it's an easy method of calculating.
1. I can't say I agree here. I'd rather constitution (or con mod) apply only once to the hit point total. I can see 1st level being 10 + con mod + hit die (roll or average or what-have-you). I like the subsequent levels not having a con mod applied, except to mitigate bad luck on rolls (as in the playtest now, where your per-level hit points are your roll or the con mod, whichever is higher, or just taking half-max of the hit dice). This could also allow for a level zero "low power" option where you haven't yet earned your first hit die.
A maximum hit die (like level 10 in your suggestion) is doable, but then you would need to acknowledge that through monster design, encounter design, campaign design (does the campaign by default change goals at a certain level?) or some other area(s).
2. Not an issue. Playtest fighters do have d10; it's just that the "tough dwarf" raised that to d12. Still, I sympathize. I like the hit-point equity of 4e far more than 1e or 3e.
4e: your first level characters had no fewer than 18 but, barring feats, no more than 37 -- a doubling in range from weakest to strongest -- and very much in parallel to the level one standard monsters.
1e: anywhere from 1 hit point for an unlucky character with no con bonus to 24 for a lucky ranger with an 18 constitution, low-level monsters tended to cluster around the lower ranges
3e: 2 hit points for the frail 6-con elf wizard up to 17 for the 20-con dwarf barbarian. Low CR monsters tend strongly towards the lower end there, too.
Even cutting out the extremes of the 1e and 3e examples, you were left with easily a highest number that was three to five times the lowest number for max hit points, and a max hit points for monsters/NPCs that was towards that lower end.
3. I can definitely agree that to-hit rolls of some sort should probably apply to wizard minor spells that cause damage. I liked the 4e magic missile in its original form far more than the revised version for similar reasons. Scaling and whatnot should be closely examined, too, so that no minor spell reaches the level of what a fighter can do on his normal attack, even with an improvised weapon. (Okay,
maybe on the level of what can be done with an improvised weapon, but no better, without some sort of investment of resources from the wizard to make his at-wills better.)
4. I like a balance of sorts. More characters should be good at skills than we've seen in prior editions, but the 1e thief was just bad at combat, and I don't want to go back there. I think 4e struck a good balance (well, better than prior editions) with rogues (and especially their thief cousins from essentials) being the kings and queens of skill usage. The damage scaling of the playtest rogue seems to be too high (higher than even the 3e sneak attack scaling), and much higher than the scaling of 4e sneak attack. Then again, with recent insight, the action cost of gaining advantage might be just enough to offset that back to a 3e level. Still, perhaps, more than I like.
I didn't get the "dig" on 4e, here, as the scaling of the rogue's sneak attack there was pretty trivial. (2d6 at 1, 3d6 at 11, 5d6 at 21; most likely changed to d8s via a feat somewhere in that progression.) 4e rogues are not the best strikers by a long shot. They are the best with skills, though, by at least one trained skill. Thieves really rock out the skills.
5. It really looks like there is no scaling of bonuses to checks, though there is obviously scaling to damage, and it looks like it needs close monitoring. The magic missile spell and the rogue's sneak attack both go up far more than the fighter's damage, and that needs to be watched.[/sblock]