Design is not optimization. You don't go from a poor solution to an elegant one by following a gradient of success.
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If simplicity is formalised, then that's a well-posed constrained optimisation problem. Optimisation ! = gradient descent
I doubt you can formalize it since you're looking for conceptual simplicity rather something superficial like "fewer lines of code" or "fewer buttons". Likewise the constraints you're trying to satisfy generally can't be formalized.