The point of bounty is simply to attract attention to a question to gain more comments, ideas, answers, and votes.
Which is just as useful with feature requests.
This allows the community and staff to get an idea of what people think, whether it's a good idea or not etc.
Then what is the point of a Bounty on a feature request that can either be Completed or Declined by an employee that will specify it in the answer section and get the bounty.
So what if staff/mods get some rep for fixing a bug or implementing a feature request.
You can argue their answer is not a valid answer as it's just a note to state job done, and so bounty and upvote rep gained from their "answer" is not as per the normal play and rules.
However, you can also argue, that an answer from staff/mod stating "I've implemented that feature you and other users have requested (by their upvotes)" surely deserved a return thank you by their gaining some rep?
As while their rep gained is not from a great answer to a question their actions were still helping the community, just as a good answer to a valid question helps the community .
Let's face it, a feature request isn't really a question that requires a great answer anyway, as we're on MSO...