I think that maybe there could be a happy medium here. With Mp-regen I do think they should remove Tranquility, Exaltation, Stygian Spikes, Siphon MP as they really are no longer needed. Basically just a useless ability. I think they should slow down the amount of MP-regen though. Currently it is way too much way to fast. It does not make people learn their jobs effectively.
In an endgame boss encounter, you can't really stop fighting, or worse, healing so you can recover mp. In ffxi sometimes you would do it, but with multiple refresh you are almost full time engaged. As it, they are far from useless