Well they kind of did, after FFII, Akitoshi Kawazu (one of the main game designers) went off to make Square's SaGa franchise which actually utilized a more streamlined and refined version of FFII's battle system.

I'm actually fine with the game's leveling system except maybe make it easier to grind magic. My main beef with the game is it's terrible dungeon design and incredibly high encounter rate, not a good combo. The inventory system was also disastrous but that's been fixed with ports.