Thanks for the review! I agree with a lot of the views you have stated.
As i've stated in another response, the initial plan was to curtail particular instruments/rhythms to the NPCs that you see scattered around. We'd have them randomly spawn and request instruments or song types that you then had to accommodate by moving instruments around.
I agree that having the option to turn off instruments would be a nice addition.
It's funny that you bring up Sound Shapes. That game was part of what sparked this idea!
To make a long story short; we just ran out of time. This rendition of our idea was slapped together in the final hour and a half as I wanted to show off our instrument pairings to go with the theme. I believe this is a novel and interesting idea. I plan to rework the code to make it fit more of a proper game with set goals and rankings to beat once the game jam voting session is over.