Another one was the “All in the Family” vehicles.
In the Cosby case, it was the producers that wanted to make the turn (LA libs). They thought the exceptional ratings was a mandate for social activism instead of just a reflection of how entertaining the show was.
An early example of “Shut up and sing!” heard at most Bono and Ditzy Chix concerts.
Interesting. I didn’t watch the show regularly (saw most episodes in reruns), so I guess I’m not sure when exactly the show turned from “entertainment” to “social activism.”