There's a problem with using Fluid Aura. If you use it on a target you're tanking atm, you have to chase it down pretty much. If you use it on secondary or tertiary targets and the tank doesn't have full aggro on them (because he's trying to keep hate on 1st target as no one's hitting the 2nd or 3rd except that WHM with friggin' Fluid Aura out of nowhere)., you're gonna have to interrupt your rotation and make sure it keeps the hate.
On second note it messes up your aoe hate skill use. Flash misses when the mob is suddenly on the other side of the map. Even worse it is for war when you have all the mobs neatly in front of you for Overpower's cone, but a random WHM thinks it's cool to reposition the mobs with Fluid Aura.
I've had white mages using it and I won't complain when they do so as I'm able adapt. But it sure is annoying.