Play every job. Play every role. If you don't enjoy one of the three healers, but only want to play healer, maybe don't play FFXIV. It's just a truth of this game's design that it will be much harder to add interesting, diverse healers. And FFXIV is not alone, other games have the same problem. See also: Overwatch.

There's only so many ways to make "wave your hands, restore numbers" interesting. Meanwhile, there's countless ways to represent swinging a weapon and subtracting numbers. Or shooting and subtracting numbers. It's not some sort of favoritism. It's just straight up harder to make healers diverse.

Also, SE didn't help by painting themselves into a corner with assuming tanks would be wearing plate for tankbusters, and healers would always be on the backline for healer-targeting mechanics.