As I believe we've gone over before, some people are happy to move with the changing times, and some people's tastes ossify in their teens or early twenties. It can be art, it can be music, it can be which version of Batman is best... but they decide "This is what I like" and stick with it for the rest of their lives.
You can't really blame them for liking what they like. That's their choice, and entirely up to them. But it does lead to a lot of the "Things were better back in the old days, the stuff kids these days like are bad and wrong" complaints, and those do get tiresome.
(For the record, I'm fine with the art changes in D&D, but I fully admit my music tastes are more for 80s throwback rock and metal. I just try to put more effort into finding where that music still exists than complaining about how mainstream American music doesn't give me what I want.)