What killed the glossy news magazines?

I just picked up a copy of the July 23, 1968 edition of Look magazine, and am fascinated by its contents, which I’m going to blog about soon. But before I do that I’m interested in the following question: Why did Look and Life in particular, and related mass circulation publications like the Saturday Evening Post, go out of business when they did? (Look ceased publication in 1971; Life largely ceased in 1972 although it stumbled through a zombie afterlife as an occasional publication; the Saturday Evening Post shut down in 1969).

Obviously some big structural changes in the American media economy killed what for many decades had been key sources of journalism, photo journalism, political opinion, and propaganda for millions of Americans. The obvious culprit I suppose is television, but other forces must have played a role as well.

In any event this shift in the information/entertainment/propaganda economy in the late 1960s/early 1970s has some striking parallels with the upheavals in journalism etc. wrought by the Internet age, and I would be interested in peoples’ thoughts on this and related topics.