Q u o t e: It has advantages (instant aiming, instant travel time) and disadvantages (low damage unless channeled, cannot move or defend while channeled, possible high mana/resource cost). What more do you want? The skill to be almost worthless?
Perhaps it was designed wrong in the first place. The rotation reaction should be modified to be slower than it is now so that it doesn't become "spammable", and thus the damage should be increased to balance it out.
The "balance" would be something along the lines of making the damage escalate much faster within the first 4 seconds, like so (in seconds):