Actually I think what Bolivar said is part of the reason for feelings. Most of the FFs I enjoy have been pretty innovative and mixed things up, whilst FFIX was a game that set out to appeal to the people who loved the first few FFs. If you didn't play those games until much later, because they were never even released in your territory, and you started with VII, IX is possibly going to feel like a much less interesting and innovative game. Lacking nostalgia appeal the game loses some of its charm - how much is probably going to vary from person to person.

Although that theory does not explain why I later went back and did play most of the earlier FFs and enjoyed them thoroughly.