Bounty questions should get bumped periodically.
I think the Community user should bump questions with active bounties aggressively, let's say 1 bump every day per bounty
I think only good will come from it; bounties will get more visibility (this is especially beneficial in the first few days where the question is buried on the third page under the bounty tab) while it won't get annoying: with the current amount of bounties on SO, an average of a bump every 15 minutes. Considering that the average on the activity tab is 3.3 questions per minute this feature would increase the tab's activity by only 2%.
Also I don't know about you but I rarely check the bounty tab; maybe with this feature implemented I can stumble upon a bounty I'm able to answer.