The problem with aery isn't that it's OP
..it's that Arcane Comet is worthless and Phase Rush is only good on like 15% of champions.
And most of the mage/sorcery champions do not synergize well with the domination path as a primary, and therefore cannot take electrocute either.
So they are left with Aery which is the only viable option for them and have to take it.
and a bunch more do better with Comet than Aery. I dont really understand why people think Comet is bad when its actually really good on a lot of champs