Players using knock-back skills freely are an issue for any class that requires melee distance.

For example, a low level tank. "I'm losing aggro on the mobs, gotta Overpo- shit he blew it away!"

There are intended to keep enemies at bay while you cast a spell. In a party, your tank's whole job is to do just that, so it's unnecessary, and any DPS you gain from the blow is DPS lost from everyone else. So unless you are fighting a baddy that can't be knocked around (like certain bosses), just set that skill aside.

As for the vote-kick, I've really only required it for a few people DC'ing and like maybe 2 jerks. I don't see anything wrong with the current system.