I'll just add one thing.

Commonly in RPGs, even quite a few single player ones... the player-controlled character is intentionally shallow. The idea is to give a blank slate that you can project yourself onto, and MMOs allowing customization at all, and especially deep customization, goes particularly well with that.

It does present some difficulties. More active protagonists with well defined and 'deep' personalities have their own flair, but can interfere with players projecting themselves onto the character they play as (which has the potential be a bigger problem than you might think). One way to sort of run around this is to have allies commonly with you that have their own personality. Then, even if you hate them or simply don't relate well, at least it's not the virtual you.

Would be nice were it not so, but the less vague they make the plot, the more specific details they have to build on. Actual input choices are difficult (though not impossible). But they can show an animation of your character talking, and let your imagination fill in the blanks for how you would talk (which is far more limitless than having a few multiple choice options and maybe 3 voice options for your character).

...It is pretty frustrating in situations like this, though, where we really want to act while our character just sits by...