Less instant casts on summoner would actually make it more fun Imo.
I think Summoner has way too much mobility for casters and it creates a situation where it's always pretty much the best choice while being easiest to pickup and play. (blm can be better? but usually summoner fits way better into teams and they don't have to play around you).

I personally would have preferred bahamut casts, as to make it feel different from phoenix, but Ideally I'd just like more casting in general on summoner as that's what I enjoy most about Magic Dps.