JMS has something new to show off...

Back when I played, I preferred any system that removed the need for MP potions, because they're an annoying money sink and inventory hog.

Really, what purpose does MP as a whole serve, besides wasting your inventory space? One of the pros with games that remove MP systems entirely, in my opinion. They almost always don't do anything, especially true for MS. At least the Mana system gave you a reason to mix up skills, even if it was only between two skills.

I find a lot of the mana costs to be annoyingly high though, and it recharges slowly, especially when the game is lagging.

I was interested in the no-MP aspect of it too when it first came out, but the way it was implemented is more of a pain than anything.
But you are right about it causing you to mix up your skills slightly, I guess.

Like I said before, it's probably better if they found a way to improve on the system rather than removing it entirely. Increasing the Max Mana would be a simple way of making it less annoying too.