They should. They could. But they won't. Because reasons.

It would make the jobs feel more unique. Hell, they don't even have to change the damage on them or attack radius/healing radius...just the animations. A DRG using Final Heaven looks silly to me. A MNK using 'Omnislash' animation looks dumb. And a SMN using meteor without any sort of egi/primal tied to it is more than a bit ridiculous. It's a quality of life issue than actually game-breaking, but hopefully eventually they'll find the time.