That would be plausible if they existed
alongside smarter SF shows, but they didn't. Trek aside, smart SF shows weren't really allowed to exist because executives didn't think audiences could handle them. David Gerrold's smart version of
Buck Rogers was rejected in favor of Glen Larson's dumb version. Shows that started out relatively sophisticated and dramatic in their first seasons, like
The Six Million Dollar Man, were dumbed down to pure action in later seasons, and shows that had ambitions to be intelligent, like
Logan's Run, were subjected to network-mandated rewrites to dumb them down.
And that dumbing down did
not make them more entertaining most of the time. It usually just got them cancelled quickly because they were too cheesy to take seriously.
Anyway, Bruce Lansbury came right out and said
in an interview that he didn't think most audiences would like a show that ventured beyond the familiar, routine conventions of TV. "Some people can't identify with science fiction. The hardware and the futuristic setting create an anxiety in some people." By his own words, he had a low opinion of his audience's ability to handle anything beyond
Mannix-style car chases and fistfights.