Been playing Beta3 Since it was released and have found slaps to be extremely ineffective and do little damage, I don't even bother trying to slap anymore, and have found this a growing trend among players, instead running away and trying to find a weapon before anything else, as there is no advantage to slapping.
Maybe some increased speed while slap is equipped and/or increased damage of slaps would make more people actually use it then not, and actually fun and worth using.