What is wrong with cone aoe?

[Shurrikhan]

Many times it wasn't the tank moving the mobs, but the mobs deciding they were going to move on their own to a tanks flank.

Except there'd have to be not even an infinitesimally small portion of their massive hitbox rings within your 140-some-degree cone for that to matter. Even well off to the flanks, unless the mob was very, very small, you'd still hit it.

Just due to sheer hit-ring size, a mid-size mob could be a few feet behind you and you you'd still hit it with your conal AoE. The mob's body itself, especially on mobs that are longer than they are wide, is a very poor indicator of where your AoEs have to hit.

needing a target for the cone is probably what made it so awkward to use for me.

That at least makes sense. Though, that seems more a problem of SE forcing certain geometries to have targets than an issue of some geometries being inherently inferior to others (despite spending their near-equal total area on a space more optimal to positioning mobs).