Two things that could make a better experience at least for me.
-Adjust battle special effects
Special effects are constantly blinding you in battle. Final Fantasy 14 has the option to turn these off or make a few selections to minimize them. The emergency code pop up its very cool but many times it blinds you at the worst timing possible. Players actually have mods to minimize this issue, it would be nice if SEGA would this on their own, instead of the player resorting to installing shady files, that could break the game.
As for sub-palettes, i know many players dont even bother with these, specially vets. However i play with a 12 button mice and and programmable keyboard so i really try to make out the most out of each sub-palette book. I hate using a weapon palette slot to be able to use other photon arts of the same weapon, just because there isn't enough hotbar slots. The idea not only feels lame but it also means that you are not able to use all photon arts smoothly.
What players do is ditch what is not all purpose photon art or tech that fits most situations because, there is just not enough slots for everything.
Sub-palettes are the key to performing all photon arts and/or techniques fluidly, especially for Non-sucessor classes that have 11 photon arts. The problem is that there is not enough books that can cover all the classes if you plan to play all classes like i do.