LMAO dude first of all I dont want dissidea. Second of all I just said the worlds would be seperated as zones (idea as an example to counteract confusion). Hell what you could do is each zone has a separate storyline. Also why do you have to be a fan boy to promote an idea. Also it would encourage people to play that would never really consider playing a MMORPG due to familiarity. Also I dont know why you bring a below par wanna be fighting game to the picture since they never have good storylines to begin with. I feel you are just salty that the game was balls. The storyline is indicative of how much time and effort you put into it. If you are arguing that it cant be done with a good storyline I argue that it can and the only reason it would fail is due to lack of creativity and laziness.
Also if you cant seperate a FFI storyline from a FFVI and FFVIII storyline you need to go back to school and learn how to read and comprehend at a proper level. If anything I would argue it promotes depth and playability. It also gives the game diversity and makes it unique as hell.
Points you didnt back up: How would the storyline be scrapped? Why would they be unbalanced? and couldnt these issues be addressed in one way or another? I think so.