This game had/has a lot of promise, and was so close to being truly enjoyable (for those who like strategic depth). If they made a few tweaks:
-- Variety of equipment (3 items at same level, but with different stats, so equipment is situational). Rather than pure linear progression.
-- Better materia customization (right now it's extremely trivial. They could borrow from FFVII and make it truly an art in itself).
-- Non-deterministic AI. It's not only boring, but rather silly, that we know the moves boss' will do before they do it. At the very least, make hard mode non-deterministic.
-- Battle Tactics. More advanced tactics (FFXI as an example since many know about it): Skill Chains, Magic Bursts, SATA.
If they added Skill Chains, MB, SATA, FFVII style Materia, better variety of equipment, and random AI in Hard/Extreme mode dungeons/bosses, I would be very happy indeed. And there is nothing stopping them from doing it. The 'casuals' (those who do not want to spend time learning/mastering a game) would enjoy all story progress without the need for advanced tactics/equipment. The 'dedicated' (those who want to learn and master a game, regardless of # of hours they have) would enjoy the need for advanced tactics in hard/extreme mode battles.