Did you stop watching TV in the 70s? There have been many excellently written TV shows since then.Doubtful there was much of anything anyone could do, the quality of SF of network TV was soon to degrade with the 'adaptations' of Planet of the Apes, Logan's Run and others.
Sadly such lowered the bar to intelligently written TV fare, SF or otherwise, that it would never return to the levels of ST:TOS, The Prisoner or Dr.Who.
Case in point, Battle of the Network Stars.
I watched Battle of the Network Stars, back in the day. It was fun, but hardly typical of TV from the last 40 years.