I agree that it is all about the distinction between ingame and metagame. In particular, it is all about which flow of information has superiority. Does the ingame rule the metagame or does the metagame rule the ingame.
Any 'gamist' inclined game says that the metagame rules the ingame. That is to say, the rules are the way that they are, the physics of the game are the way that they are, and things happen in the game the way that they do primarily for metagame reasons. For example, characters get a saving throw to avoid be pushed in a gamist game, if and only if being pushed has some additional negative consequence. This is for reasons of balance. Why do minions die in one hit? Because it makes the metagame simplier. The flow of information is therefore metagame to ingame with the metagame ruling the ingame.
Any 'simulationist' game works the other way. In game situations dictate the rules. A person pushed off a ledge gets a chance to catch the edge, not for reasons of game balance but because we can imagine that character doing so in the game world. If we can't imagine them catching the ledge, say rocketed into the air by a catapolt, then they get no chance of doing so. With the 'simulationist' the imagined in game reality determines what sort of rules that we need. If you want to catch the ledge, you have to drop your weapon because you need your hands. If the player says, "But my weapon is a pick and quite suitable for grabbing the ledges or otherwise arresting falls.", then you probably go with it because it fits even if there are no rules. "Ok, fine, make your climb check, and you are hanging on to your pick.", and then try to think what that means.
Contrary to some accusations, I'm not really claiming the superiority of one sort of game experience over the other. Both ways are fun to play. Both ways have potential pitfalls. A good case can be made for both styles. But I am very much saying which one I prefer in an RPG, but that's a different thing. As I've said before, 4e seems well designed for what it is, but it wasn't designed for me.
