[Henry_Mareck]

The way i see it, the mathematical limits to your pushing power are all that FIRST needs. Seeing as your pushing force is only created by the force of friction, you can do two things to increase your pushing power, assuming you have used sufficient motors and gear ratios. Increase your normal force (weight) and increase your coefficient of friction (tread). In theory, the only thing that matters is the type of tread and not the suface area, but in practice a large surface area is at least slightly better. As you increase the suface area of the tread, you make it harder and harder to turn, untill you reach the point where you need some sort of actuation to reduce surface area for turing purposes, or you just cant turn at all. A robot that cant turn or that has significant trouble turning is about as useful on defense as a rock, assuming that there are multiple positons that it is possible to score from.

If you didint feel like reading the giant paragraph above, to summarize:
The limits on total weight and the fact that you cant have infinitley sticky or infinitely big tread limit robot pushing power enough, there is no need for FIRST to do anything.