I don't think SNES music was better or worse. At the time is was different than other game music. The first time I played Mario and heard the echo it was awesome. Zelda music I liked, Actraiser I thought was really awesome, but then everything sort of started sounding the same. The keyboard reference is a good one. It just seemed like a lot of the same instruments were always used like on a keyboard, Sound #2 Organ, Sound #17 Orchestra hit, and then the drums always seemed to some demo from a bad keyboard.
It seemed more like it just had like these limited selection of default instruments that all game makers just selected from. So everything just sound the same, but just musically arranged a littler different.
Zelda is a good example. I like the music, but it's a very typical MIDI music like feeling. It's horns and strings, but not real smooth but more stepped/stuttered.