Its past time Anet changed wvw tower/keep/castle gates so they cannot be damaged by players DPSing them. An attacking side should need siege to break down a gate, its just common sense. Defense should have the advantage of being able to hold out if they keep taking down enemy siege.
This change would also stop the waypoint contesting abuse. Its rather stupid that a single player can run up to a gate do 1 dmg and contest it for 4 minutes.