I wonder why these 3 series aren't being rerun anymore? BBC AMERICA shows THE NEXT GENERATION and ME-TV shows The original series but the others are nowhere to be found. I wonder why?

The only Sci-Fi shows that are popular these days seem to be shows that are dark and negative not shows with a positive view of the future like those in the Star Trek cannon. The original series is a cult classic and Next Generation is the show that ressurected the franchise so they still get some play.