As I was reading your post, I kept thinking it's much because of how we listen to music today. Etc. streaming. Then you came around and touched that subject as well ind the end.
In the old days, much more work was required if you wanted to listen to other music than you already had on cd back home.
You would not go to the supermarkets, they only had the new stuff, you needed to go to the library or the music store and browse. For this reason alone I think the average joes' music knowledge and collection was more narrow than today.
Today, all the worlds' music is available on your phone. And a popular tv series can spark and ignite a flame so great that when you listen to Kate Bushs' (absolutely magnificent) song; Running up that hill, over and over, the algorithm will create a "wormhole" / open a door to the music from the past via suggestions of similar music. The users eyes (ears rather) are now opened for the older music catalogue.
That is my take an the statistics and I'm pretty sure it's one of the main reasons for the movement we see, rather than "new music sucks".