I agree with a lot of stuff in this thread, it's really just an ups-and-downs issue.
On one side, it's a matter of the worth of individuals being brought down by some, but isn't it like that for a LOT of things? Inside and outside of NW, Warband, and games in general.
On the other side, the current system reduces even more spam by allowing everyone to build freely as if they have the entire Sapper's limits at their commands. This COULD be done differently with a rationing system, but alternatively, one person's ability as a Sapper could be much more than another person's ability as a Sapper.
So it's really hard to choose one thing that can do the job. I do like to see your opinions, though.