^^^ Yeah, without a doubt. A lot of early hacks did exactly that, so Nintendo could learn a thing or two. Since we couldn't of used custom stages online (without, again, more hacks), it's not like custom stages should of been as limited as they were.
Better yet, we should be able to modify actual stages and make a seperate custom stage for it. :3 Hyrule Temple with a rediculous amount of obstacles? Why the hell not! xD