FFX:

Fix it so you can skip scenes. I LOVE the story, don't get me wrong, but I've replayed the game so many times that there are a few scenes that I'm tired of seeing....and I agree with Lunar Weaver about Tidus

FFX-2:
Fix it so I'm not doing sidequests the whole game. A sequel to FFX could have been greatness, but instead it just turned out a bit mediocre for my tastes :P