The goal of this Aura is to provide us with an alternate but punishing option for regening mana.
Arcane relies heavily on planning out the whole fight before hand in regards to when you are really going to burn.
However, especially in pug groups, this can be difficult. Having a phase push just a little too late or too early can have a significant impact on our dps.
Having a little more control over our mana regen could provide us a tad more leeway in this regard. It is for this same reason that I think we need a very inefficient but VERY rapid mana burn ability as well. (Arcane Obliteration - #3 by Magias-stormrage)
It would also help us out in situations where we need to spam Arcane Explosion.
Also, the more abilities mixing things up the more fun Arcane will be and the more creative uses of abilities people will be able to figure out. Arcane is just flat-out lacking in abilities right now.