I want to see something new. Nintendo did a very good job coming up with new instruments in the past game. The spirit flute in ST is an example. I really love blowing that flute. And the wind waker, too. New usually equals good. It gives new feeling to the players (us). =D
I don't say that the old instruments are bad (in fact, they're all awesome IMO), I just think that it's better if Nintendo makes a new and unique one.