Ryushikaize said that it was the laziness of the developers...

I will add that it was the laziness of the developers riding on the coattails of the blind successof the FFVII that the simple NAME of Final Fantasy and expectancy of even more extravagent FMVs that they thought they could get away with graphics over a poorly executed story to feed the masses to feed they're hungry pockets and egos for the suckers that never bothered to play a Final Fantasy BEFORE Final Fantasy VII...

Okay, there... I said it... And ONLY I said it... Bring it on...

But I will also say/add this: I thought it was because at "Disc 4", "we" were in a World at the intitial stages of Time Compression that the towns were "Out of Sync" with the current time of Ultimeica... But that's just my assumption. Look to previous post by Sir Bahamut for his view on this subject matter.