I don't think it was "unfortunate" for the comics-subculture as a whole that early DM fans were superhero-centric. Of course, it was unfortunate for individual artists and publishers who didn't want to do superheroes.
I said earlier that many fans at the time-- though of course, not all-- had a sense that the superhero genre concealed an untapped potential. They started getting the first sense of that potential developing with the breakthrough works like WATCHMEN and DKR, and these are still keystone works to later comics-afficianados for that reason. They also provided a business model for later, non-superhero works in terms of publicity and monetization, if nothing else.
If a comic like LUMBERJANES enjoys fiscal success today, it's because of those early, faltering steps.