i think it would help alot in many situations if they did make the change. when doing mass crowd control aoe spells the black mages work together to aoe the mobs down together so that no single blm takes all of the hate and it is distributed among all of the mages. when your targeted mob dies it just means that another mage has taken all of the hate from the rest of the mobs in the group and that leads to a dead mage quickly. at least if it continued you would help kill additional mobs instead of standing there while your party member gets killed because your spell canceled.

i agree with others that stated that i won't lose sleep if it's not taken care of, but it would make it more fun and strategic along with help organize attacks better. organization can only go so far when it also relies on luck of which mob gets crit and dies early and the chance that mob was targeted by another player causing them not to follow through with their part of the attack.