Someone sitting at a piano reading sheet music in front of them and playing perfectly–matching the proper buttons in the proper sequence in the right timing… it’s entertaining to watch people that good at anything, even if you dont particularly enjoy the music.
Or consider it “music” at all for that matter.
The music isn’t always the most amazing aspect of some concerts. It’s the skill.
When you break it down, Rock Band isn’t much different. Keys or buttons… primitive or high tech… piano, or rock band, doesn’t matter. You’re still just pressing buttons. It’s the machine doing the work. Unlike a horn or woodwind or string, not everyone can even play a single perfect note. I couldn’t pick up a violin and play an A, even if you showed me which string it was. It takes skill just to play the note. Same with blowing properly into a trumpet. You can’t just point at the valves and expect someone to be able to play that note without practice.
A piano, though, doesn’t take practice to press a button. Anyone can play a single note on a piano. Hell, anyone could play an entire scale up and down with no practice at all. It’s simply pressing a button. But strangely enough, people enjoy pianist concerts.
Press a lot of buttons… press them fast enough and in the right sequence and with the proper timing, and that’s something! It’s something not everyone can do. So it is entertaining to watch such a thing, even if you dont enjoy the music.