In my opinion the OP is defining the difference between a roleplaying game and an abstract simulation game. In a simulation game a person does not need to roleplay in order to play the game. There is no need by the players to interpret the descriptions given by the GM as anything other than game mechanics because the mechanics do not represent the world anyways. In fact, in an abstract game a GM does not really ever need to refer to the game mechanics with any "fluff" or description at all.
I'm a little confused. What do you mean by "abstract simulation game"? Do you mean a game where players do not control individual characters? What's the difference between an "abstract simulation game" where players control individual characters, and a roleplaying game?
Abstract simulation games are like 4E combat: the players must know the rules in order to play and the rules need not have anything to do with anything resembling combat whatsoever. There are no roles contained within the rules just a nifty game for players to utilize between roleplaying periods, if the players even choose to do so.
I don't understand what you mean when you say 4e combat has "no roles." There are lots of different "roles" people can play in combat - the damage-dealer, the tank, the healer, etc. - and 4e even gives those roles names (striker, defender, leader, controller). It's true that the 4e ruleset has little if anything to do with real-life, historical combat tactics - but that's irrelevant - it does have to do with the way combat works in the game.
I can't agree with what you are calling game-based design as being attributable to RPGs. Specifically as it is not a role-based design.
What do you mean by "role-based design," and why is it essential to RPGs?
"Game based convenience" is this same error repeated and the "imperfect model" hypothesis suffers from not really counting as a game at all (while it does count as requiring roleplaying).
What "error" are you talking about? And why does the imperfect model interpretation "not count as a game at all"?
I think it's important to distinguish that roleplaying cannot be done with a puppet in an abstract simulation-like game. Neither in a computer simulation or a tabletop manual simulation. It is when the player actually acts within the role because of the position they are within. "Natural law" is the only design methodology which allows this as the description is the rule. There is no difference between situation, role, and design.
We might be working from different definitions of "roleplaying" here. I would consider "roleplaying" to mean acting the way that your character would act in the game, based on your character's personality, motivations, and knowledge, which may be different from the player's own. Under this interpretation, you could still "roleplay" in an "abstract simulation-like game", if you had your character do things that he would logically do in the game world.
It still doesn't seem like we're on the same wavelength here. Here's something that might clear it up:
Do you consider 4e an "abstract simulation game," and if so, why? Can you give an example of an RPG that is not an "abstract simulation game," and explain what the relevant differences are?