Some of the better sci-fi movies aren't received well initially and take time to pick up a following. If they're lucky they go on to be 'sleeper hits' or 'cult classics'. Sure, re-releases help but a lot of it is there's a small group of people, like those commenting here, who remember a film/series and sing their praises long after the critics and mass audiences have forgotten about them.

Also, there are people like myself who are always scouring recommendations lists to see what we've overlooked. I find some very interesting movies that way.