Here is why, Yoshi says the game engine is super suck that they have to rebuild it from the ground up which also scrapping the "rumored" FFXIV PS3 few months ago before Tanaka was replace by Yoshi.

And because it is going to be rebuild from a newer customize engine; PS3 is the only thing left that can turn aside from the bad PC launch to a outstanding launch for the PS3, and is going to take another year to make it available.