My take: Basically, because older people find it harder to relate to the music. Especially pop music, which is catered to pristine, insecure teenagers and yout

My take: Basically, because older people find it harder to relate to the music. Especially pop music, which is catered to pristine, insecure teenagers and youth. They're well past that stage of life. As a consequence, they already have nostalgia embedded for previous music. Someone else already commented on the atmosphere (and whole zeitgeist) being part of that. Based on my experience with music (been an avid listener ever since I grew up) I believe it is also instruments (and certain patterns of genres) which can be part of that. Another explanation is because older people have less of a hearing range (Hz). You can try a test to figure out where you're standing.