Whatever music one enjoys is a personal thing, and depends on many factors. And of course nostalgia can play a role, but that role isn’t limited to film music. Sure you can have a nostalgic association with a film score, where you grew up loving the movie and so you like the music, but you can just as well have a nostalgic association with that pop song played when you were first in love, or that jazz piece that you associate with that favorite bar you used to go to decades ago.