The Recast on Dragonfire Dive is long (as are all the lv50 Job abilities), but as for it not being very potent...as an off global cooldown (and since they removed the animation-lock associated with it) its a nice additional 1200-1500 dmg attack (buffed) to string into the beafy part of a DRGs very long rotation.

Yes the timer is a longer one, but its far from being completely useless. Of course this is if you don't need to use it as a form of quickly moving across the battlefield.