What is the right amount of controls? Knobs? Switches? When designing an instrument this question can get many answers. There is no right or wrong, and that's what makes it complicated.
Pluto, from Modern Sounds, is an interesting instrument to study on that front. it combines various sound engines, two sequencers, effects and a generative composer into a little (yet quite spacious) package.
The process of making it was full of iterations. Paper prototypes, various controls and testing - striving for a balanced instrument that's simple, yet full of surprises. Bringing generative composition and modularity into a small standalone instrument.