A friend of a friend ran into a situation recently in which the agile product owner specified features down to exactly what every single user click should look like. The problem is, the dev team has already figured out a way to accomplish the business value in fewer clicks (better UX), but in the past, questioning the product owner has led to career disaster. How do we convince the product owner to change their mind and go along with our recommendation? What can be done within the agile model to fix this situation and how do we accomplish it?

On a bigger level: What can be done to make agile product owners better at their job to prevent this kind of thing from happening?