the position of movies in our culture has been on a continual decline (with minor bumps) since the 1970s

Amen, Roger. Most movies today are aimed at children and young adults with the cultural depth of a child. This was not the case in the era of Coppolla, Bogdanovich, Polanski, et al. Prior to the mid-80s, any film that was so dumb as to appeal to kids only was, well, a kids’ movie: whether Disney or “porky’s” fare, the premise was that kids were one, relatively minor, target demographic. Today, the mass market that really matters is the uneducated 16-25 year old market.