In my point of view, Aero is only weak when you're fighting 24 man raids because it's a 'missable' dot and that the boss usually has a full stack of dots so it won't connect...
But the fact that it's instant and has an upfront hit is nice for mechanics such as pushing barrels in Hullbreaker's Hard. It's also affected by SpellSpeed, so if you have a high stat, it can overcome Malefic 2 overall.
Aero is useful and is better the alternative.
