WoW had this. Rift has it too in a big way.

No. You need a GCD system to make such a mechanic viable. We do not have that in this game
we have timers and we have no queue.

Mages are already burdened with very harsh cast times in this game and very few Instant spells and
the instants they do get are not direct nukes or heals and they are on very long timers. Many instants have crazy long animations - Blood Rite is maybe the best example of just how crazy.

Picking a spot on the ground in the mass battles we currently fight ? You are kidding, surely ? Horrible idea, sorry.