As I like to point out to people, the Holiday Special gives us a glimpse of pop culture in the Star Wars universe, including TV shows, music, and art (the holographic dancers).
In that sense, it can be compared to Star Trek's "The Way to Eden", which is pretty much our sole point of reference for what music disaffected youth in the Federation are listening to. As such, the Star Wars Holiday Special and "The Way to Eden" are indispensable windows into their respective universes which we fans ought to treasure.