Equipment, that's what final fantasy needs back. That and a leveling system that's more basic than these wonder wheels.
RPG are all about being able to customize, and for the most part FF has absolutely no ability to customize your character. It's all about spread sheet stats, and if I have no influence over that or story why bother.
3 character battle systems should go as well. That is nothing more than a by product of Chrono Trigger, but CT allowed for combos. Unless they bring back a combo system your not engaging the player with enough battle field management. That's my personnel opinion of why I have not finished a FF since 9. Well that and time maybe a 30 hour quest would be nice:)