Right now, kick is a fantastic skill in PvE when a mob is under 50% (and does have benefits in PvP, but that requires it's own assessment). However, at all times before it, in PvE/P, it's wildly inconsistent and fairly weak. I dug into the code, and the current damage formula for it is a random roll between 3 and 2*level (3 to 100).
My proposal is pretty simple, an it's to pull your damroll into the formula ABOVE 50% hp.
New Formula: A random roll between (3 + (Damroll * 15%) to 100). Assuming that most melee classes are between 90 and 120 Damroll, this would add between 13 and 18 damage to the minimum side (see chart).