If I remember correctly there are 5 aoe reveals. 2 of them noone is using. 1 is exlusive for herald, 1 is exlusive for DH (trap reveals traps LUL), 1 is exclusive for core necro.
There is another problem, for this anet needs to make traps being able to be hitted by skills. I doubt they actually can do it and even if they can, I wonder how many issues it will cause.