Quote Originally Posted by Hawklaser View Post
Only reason gameplay of the summoners never really revolved around summons is because MP or some other mechanic prevented them from being frequently used.
It's because, functionally, using Summons is 99% of the time useless. Either do to lack of damage, better damage options, long animations, have more important things to do(healing), or due to complications which arise from those(I'm looking at you, FF9).

The only time summons have actually been strong is from a lore perspective.