gas.gas: Tbh i find funny your idea, its like telling a game like DIRT its an rpg cause you play the role of a car driver in a fictional game world.
At this point so every game is an rpg for you.
Oddhermit: You don't actually assume the role of a car driver in DIRT I'm pretty sure, though I've never played it so I could be wrong. My guess is that you control a car as if you yourself were the driver - it's implied maybe, that the car is being controlled by a driver in the game, but you're not really controlling him as much as the car itself.
I never played dirt too, it was just a paradigm, quite hylarious, to point out that according to your idea nearly every game can be called rpg.
A game to be cathegorized in a specific genre must offer some specific aspects of gameplay and game structure.
Its true that everyone could have his own preferences about many aspects, it is true that every game can have his own specific design, its also true that can be easier for everyone to define a platform then an rpg.
Anyway its very simplicistic telling that the only attribute to define a game an rpg is "Assuming the role of a character that is not yourself, in a fictional game world. "