Henry Luce was still alive then, and had a big influence on the MSM at the time. I date the inflection point of the MSM’s rapid decline to when Luce retired.
http://en.wikipedia.org/wiki/Henry_Luce
I used to work with an old guy who had started out as a door to door mailman in Birmingham, Alabama.
I remember his telling me that he dreaded the day that “life” magazine came out because his pack was so heavy that day.