You figure that if Beavis and Butthead were a timeless classic, that it would be running in syndication somehwere. It might be, but for the life of me I can't think of any place that runs old B&B episodes, unlike say, Seinfeld, which IS a timeless classic seeing as how its damn near everywhere.
I think Judge is so overrated. He did B&B then wanted to stop doing it to focus on KoTH, and his films. His films have been a bust, sorry, they have been, office space has a cult niche and its a nice little movie, idiocracy was pretty much a dud, marginally funny. So he just rode that KoTH gravy train, because, apparently, if you are an animated show on Fox, you pretty much have job security.
If Judge was that great, he would have thought of something new post KoTH, I think its more likely that he sees this as a quick way to make some dough. The idea of teenage kids who were fans of metal bands who were mostly popular in the 80's was plausible in the early 90's. The idea that there are teenage kids that listen to 80's metal and watch music videos, well, I just don't think there are many of those around now...