What does nonpop mean? Is it some kind of value judgment, like the term 'high art'? Wikipedia's tiny entry calls it a meta-genre, whose classification originated in 2001.
Its originators, Dennis Bathory-Kitsz and David Gunn, likened the term to the fiction/nonfiction duality. In doing so, they're calling nonpop everything that is not pop, in the same way that nonfiction is everything that is not fiction. In thinking about it, it seems to make sense to classify text the other way around, giving 'the real' one term, and the fictitious its negative. Regardless of which way you frame it, this brings up all kinds of questions as to what is real, to which Baudrillard, Hal Foster, and many others would have compelling theories. Most grade school English classes don't get too deep into these types of questions, when they probably should. The nonpop term is problematic because of its enforced binary between pop and everything else; in affirming this duality, it undermines its original intent to describe a meta-genre that may or may not find influence in popular music. In the end, I don't think nonpop constitutes a value judgment but is a transitional term meant to describe the utter genre synthesis happening today. Perhaps in the future a better term will come about, an earlier term will be reawakened (fusion), or (in the best case, I think) the need for such a term will dissolve.
Scott Unrein hosts a great podcast/blog called NonPop. Its name is thought provoking, as is its music, and is thus appropriate.