No not a waste of trail space---i don't ski a lot of bumps but do get the uurge every now and then so it's nice to have that option. One thing that Greek does is split a trail in half--one side moguls one side groomed. That's nice for groups to be able to ski the same trail and have verying terrain.
also nice for guys like me who are often out of shape and need to bail out for half a run