Multiple layers of appeal. For some people (in fact I'd say most people), they listen to music to elicit some form of emotional response. Or as a medium to express emotion. Like for me, when I had just fallen out of a relationship years ago, for example, I would listen to Pearl Jam's "Black" because I felt like it was almost perfect representation of my situation. Just in...song form.
At times, it's a chance to admire someone's technical ability. Again, using myself as a personal example, I drum a little bit every now and then, and I'm pretty fucking terrible. But having a certain understanding of rhythm and technical drumming ability allows me to listen to a song, pick out the drum part, and think in my head "Holy fuck, that's pretty fucking awesome. Maybe one day I'll actually get the resolve to be that good."
Not understanding the appeal of music isn't really a bad thing, of course. Plenty of people watch Netflix series or movies, but I barely bother to take the effort to see either of them.