As stated before, Epic could easily use stuff from the community. Wasn't there a pack that included MSUC winners for UT2004? And it's not like they couldn't change the art style; they did that with 2004 (slightly), right?
I think you're thinking of the Mega Pack right? That was released after the MSUC competition was complete. Phase 3 just started so it'll be a while before they do anything like that.