As I recall, the DR WHO show has been on British television almost continuously since the late 1950's.

I first became aware of it in the mid 1970's in the Tom Baker era. I was given a hardcover book growing up, MONSTERS WHO'S WHO, that was an A to Z dictionary of famous monsters, from Greek mythology, to the classic Hollywood movie monsters to Star Trek aliens to Marvel comics characters. And it included one or several photos of 1950's Dr WHO episode characters, I think the Daleks and maybe others. That was the first I became aware that the show had a long history extending way back before the Tom Baker episodes that I thought it began with.

Even in the Tom Baker era, there's a mix of sometimes childish and low-budget elements, but also some really cool monsters and complex plots and concepts. I'd love to see some of those early episodes.

It saddens me that about 3 years ago both SYFY and BBCAmerica networks were running marathons of Star Trek the original series episodes, but both stopped pretty abruptly, indicating to me that the broadcast episodes weren't being viewed by many. I suspect that as long as TOS episodes have been available on series DVD sets (I myself have a boxed set of all 3 seasons, but would still watch them when played on TV live) that the long availability on DVD has killed the market for watching them live for the most part. Those who love the original show have mostly purchased the series already.

Plus the efforts of the producers of subsequent Star Trek movies and series to discourage and view with contempt the original series, have all contributed to a loss of interest in the original series, at least enough of a drop to make broadcasting the original episodes no longer sustainable.

Maybe the only profitable way to run the original series at this point is through on-demand subscriber video services like Netflix, Hulu and so forth.