I'm pretty sure my PBS station only aired this once, and I thought it was great watching it as a kid. Just recently rewatched it recently on YouTube. I think it is very well done. I love when episodes feature the whole gang (of course, this is an hour special...)

I don't know the exact reason why this special rarely airs, but I do know the PBS likes to keep its programming current and up-to-date. So a show featuring the BSBs really puts the late 90s/early 00s date on it. (Maybe 9Story could do a remake with One Direction or something. I'm sure Muffy has a crush on one of those boys, too. )