Before going to wild extremes like allowing every ability unlocked even at low level and whatnot (not realistic at all as explained by others above), I'd like them to just re evaluate the whole leveling progression of all jobs so that at lvl15 they all have a basic combo and AoE, and by lvl50 they get the core of their job mechanics. Above would just be about what gets added on the top. They did this when reworking MNK in EW with the reintroduction of chakra based lower level variants like Howling Fists and Steel Peek for example.

And then there is the nonsensical "you unlock Blizzard 4 here, but Fire 4 only 2 levels later" -> "what do I do with Blizz4 in that dungeon where I'm synced before F4 unlocks?"

It needs a serious cleanup.