The biggest issue in my opinion, and the one I have mixed feelings about, is the difference between realistic and cinematic combat. It's probably one of the biggest distinctions between 4E and 3E.
I have to disagree on this point, but as always, it's a matter of perception.
I started playing with BECMI D&D and 1st Edition AD&D, and I've always found every flavour of D&D to be highly cinematic in terms of combat. I don't find 4E combat to be any less realistic or more cinematic than 3E or any earlier editions. It is less random in that PCs are much less prone to go down from one unlucky die roll, which I suppose does make it somewhat less realistic in that sense.
Hit Points have always been (by the rules) an abstract concept defining the overall toughness and staying power of a character or monster, although many players have misinterpreted HP as primarily being about how much physical damage a body can withstand. In a realistic combat system, one well-placed or lucky thrust of a dagger could kill even an experienced adventurer, and D&D has never modeled that very well.
From my point of view, Hit Points don't generally represent actual severe physical wounds until a successful hit reduces a character below 0 HP. Before that point, they represent near misses that throw a character off-balance, a glancing blow, fatigue, a physical blow that almost struck true but the character twisted his body just enough that it missed a vital organ, and any number of other things which represent gradually being worn-down. I feel that 4E reinforces this with the concept of healing surges; they aren't inherently magic healing abilities that individuals possess but represent the limits of physical and mental staying power that an individual can withstand before needing to rest. Hit Points themselves become a measure of how long a character can stand in a single encounter.
It's all a matter of interpretation, but even before 4E I had started to shift away from viewing character actions as a one-way cause --> effect relationship. Now I see it more in terms of resolving an action and determining the effect and then determining the game-fiction "cause" of the effect. I find it very fitting with the abstract nature of D&D combat. And I think this addresses a couple of your complaints about the 4E power system.
- Some powers (Come and Get It!) are difficult to rationalize or have effects that seem unrelated to each other (such as the Cleric's hit-and-heal powers).
- Although the limited-use powers keep battles interesting and simulate the sort of fights you see in movies, their mechanical limitations can seem jarring in terms of suspension of disbelief.
For example, in Fourth Edition Martial characters cannot use the same encounter power more than once even though they are free to use another, equally as strenuous power. There's no good way to explain why this is so and retain verisimilitude.
If you look at it such that a Fighter can only perform a "Steel Serpent Strike" once per fight or that a Fighter can only perform a "Brute Strike" once per day, then it does seem arbitrary and illogical. Arcane or Divine powers can get away with it, as the magical origin of these powers can justify nearly any method of resource management (spell memorization always bothered me, to be honest). When you take a step back and view combat from a more abstract perspective, then these arbitrary limitations can make sense from a game-world perspective.
When the fighter's player performs a "Brutal Strike" and makes a successful hit, expending that daily power, it doesn't have to mean that the character only made that single attempt to perform that maneuver nor that the character doesn't keep trying to perform that maneuver. In order to successfully perform a martial combat power, a great number of factors have to come into alignment just right: the hero has to be in the perfect state of focus, the opponent needs to be slightly distracted, the hero and his opponent have to be just the right distance from one another, the opponent has to have been thrown off balance or weakened, the hero's attack has to build on the momentum from the last swing of his weapon, the opponent has to expose a weak spot at just the right angle for just the right amount of time, the hero's weapon has to begin its arc at just the right moment in time... You get the idea.
For an encounter power, the circumstances in which a maneuver has the potential of being successful happens about once per battle; for a daily power, the right circumstances are aligned only about once per day. 4E is simply giving the player (not the character) the ability to decide when this actually happens. When the fighter's player decides to attack with a "Steel Serpent Strike" and hits successfully, it is at that point where we can describe the action (in the game world) as the fighter having slashed his sword across the back of the orc's knee, slowing him down. It isn't that the fighter can't be trying to stab other orcs in the knee or foot during that encounter, but the player has decided that the infrequently-occuring situation where the orc has exposed the back of his knee in such a way that his fighter can take advantage of it happened this round and not in a future round.
You may not accept this, and I have read many objections to this perspective on this and other forums. It makes a lot of sense to me, and it means that I can explain limitations on martial powers in terms of how often everything that needs to happen in order for the opportunity for a specific maneuver to be successful is likely to occur. I can still explain limitations on arcane powers as physical or mental limits on channeling energy, or physical exhaustion from channeling powerful magic. Limitations on divine powers may represent how often the gods or their servants are willing to answer prayers. 4E allows for very flexible interpretations of game rules within the narrative of the game world. Powers of all sources have the same basic structure and are limited by the same resource management system, but they can each be described in completely different ways.
The "Come and Get It" power forces enemies to move, but it doesn't have to be interpreted as some magical-but-not-magical compulsion that overrides the opponents' will and forces them to approach you. It simply describes the outcome -- each opponent in a close burst 3 shift 2 squares and end adjacent to the fighter (if it is possible), and the fighter attacks each adjacent opponent. It could be as simple as the fighter taunting his enemies and they are stupid or angry enough to take the bait. It could also mean that a group of opponents moved in such a way that they ended up adjacent to the fighter and he took advantage of the opportunity to catch them off guard. They could have been moving at the same time intentionally or unintentionally, they could have been coordinating attacks on the fighter or just trying to get away from someone or something else. The player (not the character) is making the decision that the opportunity for multiple opponents to shift toward the fighter so he can attack them is happening now. Powers essentially just describe outcomes and effects and give a measure of narrative control to the players; they can be described and explained in any way that works in the particular context in which they are used.
It's a different way of thinking about the game, but I find it very liberating and it really brings me back to how I played the game when I was younger. 3E is a great system and I really enjoyed playing it, but I do think that the nature of the system encourages a more rigid cause-and-effect mindset and a less abstract view of the relationship of the game rules to what is happening in the game world.
I think that this perspective accounts for why D&D has never really had a system of modeling specific injuries to body parts or a robust called shot system. AD&D's minute combat rounds made it explicit that the one (or perhaps two for higher-level characters) roll "to hit" made per round didn't mean that the character only swung her weapon once; it represented the overall chance that the character was able to land a blow that had an effect on her opponent. Targeted strikes didn't really work when combat was played out at this level of abstraction. The player rolled a high number on the die roll for damage and the opponent went down? "You slice the goblin across the neck for 8 points of damage, mortally wounding him. He collapses to the ground, bleeding profusely." The player rolled 15 damage to an orc, taking it to -10 HP? "Your blade pierces the orc through the heart, killing him instantly." It was generally assumed that characters were always trying to take out their opponents as quickly as possible with as little physical harm to themselves and their companions as possible. Delivering the killing or crippling blow to an enemy essentially meant that the character had taken advantage of an opening to strike a vulnerable body part.
Combat in Third Edition (and previous editions) is designed to simulate a fantasy world (aside from certain abstractions, such as 6-foot swordsmen being able to kill giants with their blades), and combat in Fourth Edition is designed as a playable action movie scene that eschews realism in exchange for excitement. This approach to combat colors the rest of the game; in Fourth Edition's case, this approach rendered the game nearly unrecognizable as the newest edition of Dungeons and Dragons.
I think that the realism of combat comes from how the actions are described within the game's narrative. If you want martial powers to represent nearly-supernatural comic-book or action movie abilities, then describe them that way. If you want fighters to be able to control the movement of enemies with their sheer physical presence and willpower, then it can be described that way.
If you want martial powers to represent the abilities of highly trained and skilled warriors, then they can be described that way as well. Many martial exploits are essentially very specific instances of a "critical hit," except that the player gets to decide when they can happen. If a power hits for 2[W] damage and shifts the target one square, then describe that as a mighty blow that knocks the opponent off balance, causing him to stagger a few feet back. If there is another enemy adjacent to the target, then maybe describe it in such a way that the target's ally grabbed him and pulled him out of the way of the fighter's swing, turning what would have been a fatal blow into a serious but not mortal wound. Don't describe damage taken as a serious physical wound unless a character drops to 0 HP; "Damage" taken can be described as the process of wearing down your opponent and forcing him to lower his defences. When a character is out of (or can no longer make use of) healing surges then her defences are just about to break and she's almost out of staying power.
Of all of the versions of D&D released so far, I think that 4E most readily lends itself to running a low-magic campaign -- which often (but not always) is seen as part of a more believable or realistic game world. Healing surges mean that magical healing is no longer necessary in order to keep PCs from dying. Martial classes cover the defender, striker, and leader roles, leaving only the controller role unfilled. Martial characters could still learn and study rituals (some such as Raise Dead would probably need to be "banned"), and that would keep the flashy combat spells out of the game, leaving magic as a difficult, costly, and time-consuming resource.
A believable game world, in my opinion, is created by the narrative and the DM and players' descriptions of character actions in the world. The rules describe quantitative effects and outcomes of actions, but they allow for a great deal of flexibility in describing how those effects were created, if the participants of the game are open to the idea.
