I don't think building new parkour maps is very high on the priority list at the moment (except for adventure parkour, I think).
The dropper wouldn't be a good idea in my opinion, since the maps of CCGN should be unique (this is why the old SCB maps were removed).
They could of course make custom maps, but that would take a long time, because one level in the dropper usually doesn't take that long to complete, since you're falling.
Mazes would be pretty cool, I have no idea if this has been suggested before?