FATEs aren't the problem: zerging FATEs is, especially when they're done in a matter of seconds after they're up in most crowded zones (which are selected because they offer the best potential in that very matter).

Even if I would not like to level as fast as possible, I would still do some FATEs here and there. Hell, I even do FATEs if I'm the only one trying it (in some obscure zones). Thing is, you can't enjoy the game the same way once you finished every quest. You gotta find something else. You could farm mobs for 250-500 exp a pop, but it wouldn't be better than zerging FATEs and would take way too much time.