How would you feel with a procedure in which your brain was scooped out like ice cream from a bowl, and replaced with circuits that would do a better job of your life for you?

One way to answer that might be to argue the counterfactual. How would I feel if I were born in the state described in the story -- little or no gray matter, but endowed with the promise of a successful, enjoyable life, valued and respected by those around me -- and someone offered me an earring whose advice would give rise to uncertainty, self-doubt, and a constant, nagging awareness of my own ignorance and lost potential?

What incentive would I have to continue wearing that earring?

For that version of the story to make sense, you'd almost have to make it a cursed object that couldn't be removed once equipped.

Well in that version you basically don't have the ability to make the decision at all. And it's unclear at that extreme if you're even enjoying things anymore.