As someone who has been healing almost entirely since... late Stormblood? I'd say that at this point it's less about class fantasy and more just enjoying healing. I'll admit I only really play AST because it's a lot more flavorful and interesting than the other healers because of how cards and seals work. But honestly I don't care a whole lot for any of the class design, I just like healing. If I could choose I would much rather a dark-themed healer or a eastern paint-themed healer, and from a roleplay perspective I get a lot more joy out of something like PLD or RPR. I might suggest tanking or support dps if you want to still have a meaningful role, but yeah healing could use a bit more love and attention compared to other roles. However I do not think any of them are unplayable like some do, I just think they're a bit plain and repetitive compared to many of the other more unique and intricate class designs in the game.