I may not be a huge fan of how FF cameos are handled in some KH games and while may have not gotten into KH for the FF stuff(At the time the first KH game came out, I didn't even know what FF was), but I was still bummed that we didn't get any kind of appearance of past ones. Sure they might not be essential to the plot, but I would've liked to check in on the TT or RG crew again(Maybe following up Squ-"Leon"'s letter from the end of 2?), a conclusion to that Sephiroth v Cloud subplot, and/or at least a cameo FF character in Olympus. They might not be important, but I'd prefer some sort of appearance of the actual characters rather then just minor easter eggs here and there.

You know, thinking about it, there was indeed a lack of Final Fantasy characters in this last Kingdom Hearts, yes there had been mentions but their presence in the story was simply nonexistent.

Compare with Disney where not only had many recurring characters/worlds returning from previous games but also new characters/worlds (Ratatouille, Monsters Inc, Toy Story, Frozen and Rapunzel).

From Square Enix there was nothing old and/or new, not even characters from the last FF game had make an appears.