Electrons exhibiting negative charge is something that would be difficult to fix because the fix would result in a lot of confusion. Using tau as the circle constant doesn't cause nearly as many problems. I don't see it as a joke; we should do it.
Actually, in this case, there's a particular discipline that's especially inconvenienced (physicists, due to the torque conflict). Contrast with j: there's a particular discipline that benefits, and they use j=sqrt(-1) all the time.