Let me preface this by saying I'm glad they introduced some form of auto MP regen. It should have been there from the start. But I feel it's far too much in it's current state.
MP should not regenerate as fast as HP. This totally removes the challenge of managing one's MP. I see this as a step backwards for the battle system, honestly.
Now, I do agree that there needs to be some form of MP regen. Even though MP wasn't that difficult to manage before 1.16. Melee classes also rely on MP, and if they don't wish to level THM to 20 for Siphon MP, then an auto-MP regen is even more important to them, of course.
However... my observations put the current MP regen at 8mp/second. That, I believe, is far too high!