Immersion

[Niwashi]

Western RPG is often more about how the player would act under those circumstances, hence choices are given and alternate courses of action are available. But JRPG is often more about becoming the character, hence player choice is mostly irrelevant, it's not about us the players, but it's about putting ourselves in the shoes of the protagonist.

I never minded putting myself in the shoes of the protagonist rather than the other way around in any of the single player Final Fantasy games, and in nearly all of them (all except the very first one) SE decided everything about who the characters are and what their personalities are, in addition to the story that's going on. While there are certainly some characters I like more than others, I never got the feeling that I should have had more control over who they are. (In fact, when I looked back at it after playing a few of the others, the absence of pre-determined personality in the first game's characters seemed a bit of a weak point in it.)

But in an MMO, due mainly to how long people spend playing them, more time and attention is spent on things we can do on our own or among our friends than on the main storyline. (That's true even among those of us, like myself, who regard the story as the biggest draw and primary focal point of the game.) That makes a lot of people want more control over just who their character is.