Technically there were so many changes between FFXII and its International release I felt it actually warranted a new game. Though the FFX and X-2 examples are certainly inline with this.

I really don't like the idea of story being added, partly cause I'll always feel like it should have been there in the first place, but to be honest, I never cared for DLC, half of it is either stuff I felt should have been there to begin with, and the other half is irrelevant gimmicky stuff like costumes and weapons. I feel the DLC model works for some games like FPS, Racing, and Fighting games, but I feel RPGs or games with strong narratives in general can't really add content cause the main course is story and I don't feel like paying 5.99 for an extra dungeon and story segment that adds a world shattering plot twist to everything or adds much needed character development to someone, cause I'll always feel like I was cheated out of it, even if the stuff was actually written after the fact.

Shallow irrelevant stuff like special weapons and outfits would be fine and I can even see the appeal of a new optional dungeon or two. I am curious as to why SE doesn't do this very much, hell even Duodecim's DLC has dried up.