Actually, FFX had voice acting too, so that probably added to the wait. Back in the days of the SNES and Genesis the translations were difficult and slow because each text balloon was a seperate picture, and had to be replaced one at a time. I don't know if newer games are the same (I know that FFVII was...) This is a poduct of the sheer number of Japanese characters available...
I'm not sure why they don't do both at the same time. I know that Japan has a much larger RPG market, so they make sure it's a hit over there first. (I can't imagine a FF game not making it over here anymore though...)
I think FFXI has a storyline to it too, but we shall see.