Originally Posted by
Mistral
The expense of engine rebuilds and redesigns, most likely. I'm not sure if you noticed, but based on the trend of their recent remakes, they seem to be shifting from the older straight-remakes exemplified in the PS1 Final Fantasy Chronicles and Anthology to fundamental redesigns along the lines of Final Fantasy 3 and the first SaGa trilogy, all of which had completely new engines built for them. Even the recent Chrono Trigger DS remake had additional content added to further integrate it with Chrono Cross despite the fact that the latter game is over a decade old by this point, in contrast to the more superficial tweaks in the PS1 remake included in the aforementioned Chronicles. As pointed out by Ray, any work on 7, 8, or 9 would require far more work to update from the Playstation 1 engine and graphical limitations to the PS3's capabilities and modern expectations, compared to the relatively minor work of the PS2 engine of FFX that already had reverse compatibility with early versions of the PS3. Squeenix doesn't seem willing to half-ass it, and even if they did, the fan outcry would be...entertaining, to say the least.
Still, a remake of Final Fantasy X is an interesting choice, come to think of it. I wonder if they're planning something else with the PS3-compatible engine that would result from such a remake, given the relative lack of time between the original release of the game and now (it's planned for the ten-year anniversary, but even so, in terms of game generations, it's less than one would have normally expected).