It's all opinion of course, but I personally am not a huge fan of inertial movement. It looks great in motion, absolutely, but from a gameplay control perspective it's really frustrating sometimes, such as during boss fights.

Say you need to run away from a crack in something like Ifrit. I push the movement key, and my character starts moving slow, then faster gradually. When I get to the spot where I want to stop, I have to compensate for the inertia by letting go of the key a little bit before I reach the point where I want to stop. If I release the key on top of the spot where I want to stop, I overshoot it. On top of that, I can't cast any spells until my movement (including inertia) has completely ceased.

Perhaps the current behavior is also due to server lag reasons, but in any case, "crisp and clean" feeling movement is always something that I will prefer, even if it doesn't look quite as pretty. Gameplay trumps graphics any day for me. Just my opinion though.