I think you're right that having skin in the game is critical. It's important to have real accountability, so if there's painful design flaws, the expert feels it.
But it's easy to think it should have been done differently and better when you don't have the perspective of the designer. I still vividly recall being a junior engineer and thinking the design decisions made by the "expert" were ridiculous, and talking with the expert, and finding out I didn't know everything and I was wrong. Thank goodness he was patient.
