I would happily trade Cure 1 and Fluid Aura for a couple extra DPS buttons. Cure 1 could be made to upgrade into Cure 2, and Fluid Aura can probably be repurposed as a DPS ability (it's tied to a quest so might not be possible to just delete it). Medica 1 is fairly useless too at later levels because of Assize and and Afflatus Rapture.
For AST the abilities to toss are Benefic 1 and Undraw. Benefic 1 can get the upgrade treatment, and Undraw can be deleted since I don't think anything references it. Helios is a little harder to let go since AST has fewer other AoE options, but I wouldn't miss it too much.
I haven't played SCH in this expansion so I'm not sure what are the useless buttons there.
GNB can execute Gnashing Fang combo without interrupting Keen Edge combo. DNC can execute dances without interrupting combo. Same with NIN's ninjitsu. And many of MCH's attacks. There's plenty of precedent of non-combo-breaking abilities, so the same could be applied here (as long as you don't abandon the DPS combo for too long - but if you do need to do enough heals back-to-back that the combo is abandoned, then the heals were probably more important anyway).