I think that the new Aoe deal isnt multidotting, but taking frost bomb and flamestrike AE/Blizz .
People...blizz doesnt sucks. Take a look...
AE does a good amount of dmg but we have to be in melee range. "so I'll just use blizzard". Ok blizzard is a chanelling spell that have some cost of mana... So in fights that we cant go melee range, for a lot of reasons like fire on the ground, mechanics or you need to be stacked with healer, use blizzard. In fights that you are interrupted, cant cast and stuff use AE..
Also, we have some stats that scales with both spells. I guess that a lot of haste = blizz > AE, for instance... But, im not good on these maths and I'll let someone do it