It seems to have been made in fairly bad conditions, by people who weren't entirely sure what they were creating, but it all coalesced. I also think that the movie itself is more signficiant that the audience routine that has grown up around it, although I suspect from the inside that can still be a powerful thing. I listened to the soundtrack + Australian audience feedback a _lot_ at one point (many years ago), and it must be said it also was a lot more coherent than what we heard of it on the DVD, which had mostly descended into cacophany.
Apparently Stephan Elliott (Priscilla, Welcome to Woop Woop) was supposed to be remaking it at some point, with Maryln Manson's name attached. It seems to have gone away again, which I can only think a good thing -- in part because I don't think they could keep the central naivety of the characters (Brad, Janet, Frank-N-Furter and Rocky are all innocent in their own different ways) that gives it its power. Whilst most people were disappointed with the 'sequel', Shock Treatment, we didn't mind it. There's also another movie that sort of follows on -- Jim Sharman came back to Australia and made a more conventional movie that nonetheless uses many of the images of RHPS, Summer of Secrets.