My theory is that it isn't just music - what people often prefer in most categories is the "familiar". When you're young, it's all new so we explore, but after a while we gravitate towards things that are like things we already know.

Having said that, what saved me from being stuck in the 80's was almost single-handedly Scrubs, the sitcom. Joshua Radin, Jon Mclaughlin, Colin Hay (re-introduction), Matt Nathanson. Wish I could find another source as good as that again.