For me 'Firefly' hits on the answer. There is a complete lack of competition in the scifi genre. You have the comic book series and you have whatever mediocre "scifi" that SyFy/Space put out. Growing up there was a massive amount of scifi to choose from, from Star Trek to Lex and everything in between. There was an analysis done on imdb data, I can't find the link, however, it showed something like 7 times the historic average during the 90s. These shows have massive followings to this day and they create revenue streams outside of the show itself with toys/games/models/costumes/etc.
For me personally, I watch any scifi that comes out no matter how bad it is simply because I'm trying not to re-watch my library for the 8th or 9th time.