The reason why Archers are chosen over Melee is quite simple.

Archer do just as much, if not more, damage than melee, without having to interrupt themselves to avoid AoE or put themselves at risk of being struck by said AoE. I've learned that the best place for a non-gladiator melee was on the sides of the Void Slave, however with Inferno drop, you still need to stop DPSing and move out of it's range. Archers have just as much reward as melee with none of the risk. Neither the dungeons, nor the archers need nerfs, melee classes have to be given buffs, to match the amount of risk associated with being on the front lines.