Someone else in this thread said something very smart: there's an essential tension in D&D. There's tension between the role-play and wargaming aspects of D&D's heritage, and of course the tension between "realism" and "game-ism".
All RPGs will have this tension. I agree with the original poster that it's impossible to resolve this tension -- the goals of "game" and "reality" are mutually exclusive.
So the thing that makes D&D so successful IMHO is that it finds a good balance between these contradictions, and allows enough breadth of play-styles to accommodate vastly different players
at the same table. It's no-one's perfect game, but everyone's "good enough" game.
And that's good enough for me.
Cheers, -- N