[Even more D&D nerdery! More abstract than the last few, and a little polemical in tone. Enjoy, the like four readers who are into this stuff.]
It's not good to think too hard about the 'simulation' side of D&D's combat system. It's not a simulation, it's an abstract tabletop combat game. Remember, a round of combat in D&D 4e nominally represents six seconds of gametime - meaning a 'hit' means not a single blow but a debilitating advantage, a net infliction of pain and constraint on the other guy. Enough wounds to matter. (You can imagine, within the D&D combat subgame, wearing down a creature without drawing blood and then finishing it off with a single swordthrust.) If you don't get hit in melee combat it's still reasonable to assume that the other guy dinged your armor or nicked your earlobe. It just didn't cost you combat effectiveness.
Failure on a 'to hit' roll doesn't mean you don't hit, it means you don't overpower. A hit isn't a hit.
Which is to say, if you're up for a while against an opponent you can't seem to hit - but keep coming close, missing by 1 or 2 on the dice every time - it's reasonable for you and the DM to roleplay some kind of combat engagement or harrassment short of lasting damage. The combat is still a good one, still worthwhile for both opponents, even - especially - if no one's able to get through.
Orcus isn't impressed by your level 4 rogue, of course, but if a level 25 character couldn't actually damage the demon prince, Orcus can't simply ignore him either. Gametime and campaign time are screwy; you could theoretically advance to level 30 in a few months of gametime, though that's bad campaign/adventure structure. A character who's been around the bend, though, and adventured for years of gametime, should be worth paying attention to even if he's numerically inferior. The player's skill should matter as well. That's where the narrative demands of campaigning supersede the numerical constraints of D&D's combat subgame, which after all isn't a simulation so much as (Final) Fantasy Chess.
This is to say, however, that the D&D combat subgame is adaptable to a whole host of cinematic/literary combat styles. Psionic combat doesn't draw blood, it weakens the mind; hit points are a measure of emotional resistance. Swashbuckling swordfights might treat hit points as momentum and combat awareness - at 0HP you simply look away at the wrong moment and get skewered, or bashed, or sliced. In the latter case, D&D 4e's 'healing surges' represent steeling one's resolve, restoring focus; in psionics they might mean a moment's meditation (a la Qui-Gonn behind the laser barrier, in Episode One of that silly fantasy trilogy) or the recitation of a focusing koan/mantra. A medieval knight's 'healing surge' might be nothing more than the rallying recitation of the maiden's name for which he fights, and hit points might represent for him a failure of faith which makes combat impossible (and so he 'lays down his burdens' and aborts his quest - at which point living is pointless).
Gametime being malleable and 4e's health mechanics abstract, it's up to the players and DM to decide exactly what flavour the combat subgame should have. This raises a question: if the flavour pushes certain mechanics into nonsense, should the mechanics be modified or jettisoned? My sense is that the answer's always YES: this is one way the 'old school' ideal of 'rulings not rules' is not only compatible with 4e but secretly essential to it. The combat system is very specific and heavy on physical/spatial mechanics - shifting, opportunity attacks, ZOC's, forced movement, combat advantage, etc. - but many of those mechanics are wholly arbitrary (diagonal movement equals lateral movement? What now?!) and should be rigidly enforced only to the extent that they make for better, more evocative roleplaying experiences. Time in the game is a consensual hallucination; we measure it in rounds. Space is as well; we measure it in squares. But squares and rounds are devices. As long as the players and the DM are working within the same frame of reference - and rulings don't take make gameplay impossible or even prohibitively frustrating - 4e players are as free to ditch the rules as 0e grognards.
But a generation raised on video games isn't likely to see it that way right off.
Which is why 'old school' players should be reaching out to 4e players and saying 'You've got your mechanics - have you tried playing in this style within that system? Did you know there's a decades-old rule system built around this style of consensual social adjudication?' Then there's the matter of the 0e/1e rules shortcomings, starting with their style - but that's not for today, thanks.
Many modern Mac users never open up the Terminal app, so they never see their machine from the command line's perspective. Alas. That doesn't mean it isn't there, that they can't modify their machine using text commands and dotfiles and Perl scripts - it just means they're benefitting from the system's power and interface refinement without availing themselves of its mechanisms of customization. Same system, less tinkering.
'Old school' roleplayer types seem to see 0e-style games as UNIX systems (huh, fancy that), infinitely customizable and charmingly baroque/forbidding/ugly; and they depict D&D 4e as the equivalent of a Windows box.
But that's to misunderstand computability and interface design: 4e isn't a Windows box; it works cleanly and with little fuss every time, and is constructed to make system-wrecking oddities unlikely or easily fixable. Naw, baby, 4e is a Mac. Nice interface promising a clean, very consistent experience with pretty colours, and the motherfucker's running a decades-old BSD operating system underneath - which you can dive into whenever you'd like. Most users won't, because they don't need to. But that says nothing about the system and a lot about its users. (And if the system is increasingly popular, this comes to say something about all users - mere humans in other words.)
When they wanna get nasty with the single-use command line apps, the 4e kids won't need a new system. And they sure as hell won't need to go back to an older one. They'll do what the previous generation did and learn a little bit of puts 'Hello world' (or the equivalent in your fetish-language of choice), and then they'll start showing the old fellas a thing or two.
And the best of the old fellas will love it, and no one's party will be cancelled. Nice.
