True, but too much instrumentation is also a problem.

I'm into synthesizers, which run the gamut from bleep-bloop toys to movie-soundtrack in a box.

Mostly, synths are marketed like 'Not only can the Omnicron Neutron Wrangler produce any sound imaginable, it can produce more of them more loudly than the competition and audiences will surely be impressed by your mastery of its mind-bogglingly vast control surface.'

But the synths which end up being well-loved classics are not the ones with the biggest range or the most controls, they're ones with a decent range which is designed and calibrated well enough that it's hard to get a bad sound out of it - meaning they don't have too many abrupt phase transitions or nonlinear feedback loops that could cause you to suddenly lose control and turn an interesting complex tone into noisy garbage.

That's true, but the design constraints are very different. If your synth had a system in it that could fail, and another system responsible for monitoring that first system, and potentially overriding it, and if that system failure required you to take immediate and very specific action to prevent your synth from turning into a fireball, you'd want probably want a more or less one-to-one mapping between those subsystems and the instrumentation that you're looking at.

The well-loved classics you describe sound more like making a plane that's aerodynamically hard to lose control of... which is kind of a holy grail, but the MCAS design came after all of that was fixed by earlier design decisions.