Had an interesting discussion awhile ago with a student where we came up with a theory that has probably been discussed elsewhere, though I'm not immediately aware if it has (the subject came up recently in another class I'm taking, and it reminded me of this):
The sum total of the freedom of a game designer to create the world, plus the freedom of the player to alter that world, is a constant.
An RPG like Final Fantasy that has more or less a linear, established plot gives the player relatively few choices in terms of affecting the game world; the player may have different strategies for beating monsters over the head with sticks as efficiently as possible, but at the end of the day they're going to save the world, rescue the princess and kill the evil wizard all the same.
Compare to Fallout or the Elder Scrolls games where the player has more control over the game world, but now the game designer is constrained: it's easier to create a world, but harder to tell a compelling story within that world.
I think this is, by and large, the difference between Eastern and Western RPGs.