Now that the Acceptance Rate is implemented for all users, I think it can be useful to put back some of the unaccepted questions in the Unanswered Questions group.
I'm saying this because some questions are not marked as answer simply because a suitable answer hasn't been found yet, at least from the question asker perspective, even if there are upvoted answers.
If an user has an high acceptance rate (>80%, for instance) then it is expected that he accepts all questions except the ones that he considers not to have a valid answer.
Therefore, for these users, the unaccepted questions should be considered unanswered.
I'm not entering in details about the rules, it's just to give an idea and ask for your opinion.