@Rossi

Would you take it as a your 31 point talent? In Fury or Arms tree? It's not like anyone is saying Dispersion is useless, especially in a PVP setting. For PVE though it is not that impressive an ability. It is a nice ability but its uses are limited. How would a fury warrior feel if I took away titans grip but gave them a 90% damage reduction ability? Or what if enhancement shamans had a buffed up 90% damage reduction shammy rage instead of spirit wolves? If you consider the fact that many boss abilities this expansion have pierced through Dispersion and you get what you have now with spriests. It's not a bad ability. It's just not a class defining 31 point ability that almost all other specs get.

@Avan

Without being able to cast mind flay and mind blast your DPS drops dramtically. The point is this Avan, as a PVE spriest you try to avoid reasons to use that ability because of the loss. Ideally, a spriest will NEVER have to use it. It's just not frickin cool that our 31 point ability is a button that we never want to press. And when we do press it we immediately want to turn it off, as you already pointed out.