Should feature questions be required to give out bounty for those who try their hardest in answering a question? I think that the person with the highest ranking score after the seven days should AUTOMATICALLY get the bounty unless the asker gives it manually beforehand. The asker doesn't have to say that was the answer by hitting the check mark but the people that work hard in finding the answers and have the highest POSITIVE score should get it.
What you've described is how it works already.
When the asker doesn't manually award the bounty, it goes to the highest up-voted answer posted since the start of the bounty. If no new answers have been posted (or none have received upvotes), the bounty fades away into the ether.