If it weren't for Hacker News, I would not have heard of Drawing on the Right Side of the Brain, which I'm currently reading. I had also never heard of The Inner Game of Tennis despite playing tennis for four years in high school.

To your point, some of the books were hugely successful when released, but don't receive much attention today due to the newer books in the spotlight. We all live in different worlds so some books will be wildly popular to some groups and foreign to others.