What do you dislike in ATB Systems?

[RosyPosy]

So is it because the atb feature set hasn't been expanded enough to make atb systems to have unique values, or is it because the very essence of the core atb concepts are just... "self-defeating"?

Self defeating. though if you made stuff like haste much stronger then it could add to strategy at-least.
Simpler math instead of 150% or 200% increase just make it insane like 300% so it guarantees usefulness. raise its cost to justify the power.
If you dont want your atb to be really annoying speeding up the required fight time will do that- making all enemies and allies defeat-able within 3 -5 hits (at the level your supposed to be when you get to that area) Stuff cant miss as often so the level of speed should basically guarantee a hit- unless Slow\stop or the like. just make sure every move you have in the game is a clear advantage if used. If an enemy is weak to fire He should be down in 2 hits to it.(at same level) If hes resilient He should triple his defense agianst it. showing how ineffective it is to the player will force them to think of different options.stuff like that will rob the atb of time to annoy us.