As for BRIT25C, I will acknowledge that
@farmerted555 probably has a better knowledge of the show than I do(saw the premiere at the crappy local theatre when the producers were trying to pass it off as a real movie, watched the show a few times). With that caveat...
Two seasons seems about right to me for a late-70s TV space-opera aimed at easily-distracted pre-teens, and coasting on the popularity of Star Wars(Battlestar Galactica, despite its now iconic status, only lasted one season, by way of example).
And when you're having to rely on gimmicks like Gary Coleman playing The Two Million Year Old Man, well...