Not only is rust about killing things to survive, but to enjoy the nature of the environment. I think making instruments playable in a more unique way would add some nice beautiful user created art.
To go about this I was thinking that each instrument uses full control of the player (with a quick escape button!) and remain in the world once exited.
The next part is to incorporate a system to register keyboard strokes as different notes with maybe a modifier button for extra effects. This will make clans more exciting and the lone wolf a call for fellow musicians or his next meal >:p
Sorry if anyone has already mentioned this or anything like it, but let me know what you think and vote!