I'm only joking about adding Goku in. I really don't see what difference a Smash Maker would be. The customization aspect of Smash for Wii U/ 3DS was made so people can well...customize their experience. If you want someone in your roster go make them. The options are somewhat limited but I think they'll refine it in the next version.I know you're joking, but that really does seem to be the way they are treating Mii fighters.
I would love for there to be something like that. Got done with Plague of Shadows and I'm now onto the challenges. It's really good and it shows the potential for this kind of thing.