Yeah, definitely. I just figured that a custom stage would warm more people up to the idea. I'd be for something like Smashville as the first stage, though I'm not familiar enough with all the stages yet to pick one for sure.The thing is, couldn't we just use a regular stage as the first stage? Like, let's say Castle Siege. It changed into three different types of stages in a set order (not random like Pokemon Stadium) so no one character has an advantage in the terrain. I don't think we really need a custom stage to do that. Although personally I do like the current system.
Honestly, I think that it's better to have a static first stage that's consistently better for X characters than to have a random stage. It's a much better way to design a competition to have character selection after the stage is known. Sorry for getting off topic.
I don't see any real negatives for using a custom stage in tournaments, unless the host(s) choose/create a very poor stage. Getting the stage on everybody's wii shouldn't be difficult. It can be copied over when you check to see if the save data meets the specifications.