I don't mean that I have to directly identify with whatever they're creating but when someone is singing or playing a song, on some level you like to think about what they were feeling when they wrote or performed it. Likewise, something that always made me feel affinity for a band (especially as a teenager who was learning to play music) was the feeling that this was something I could do myself if I spent the time or developed the skills. I was drawn to a lot of punk bands and bedroom experimenters because I heard things that sounded like something I would do if I was more talented or experienced. It's hard to explain but it made things feel more personal. I think machine-generated music could certainly exist and be programmed to be indistinguishable from human-generated music but as soon as I knew it was created solely by algorithms, I'd lose much of the intangible (and irrational) connection I might have shared with the actual art.
On a purely musical level, there are already some artists that I really enjoy, who I suspect use algorithmic composition heavily in their music. I was wondering about this one the other day, since it's sort of similar to algorithmically mashed-up sample pieces that I've made (but better):