A lot of people can utilize motion capture. It simply makes things far more realistic than can be achieved with merely moving a model in keyframe. And of course, purchasing such animations is cheaper than the thousands of dollars that a proper professional mocap setup costs. Also while I can see great advantages from melee fist animations there are limitations in that such actions might not align with many of the desired physical actions. But things like choke holds, throws, and dragging a person would all be great inclusions into such a set.
Personally I have needs for such things as climbing over a wall, crawling along the ground, tossing an object, tossing an object from cover, and pushing / pulling large object.