Personally, I have encountered bounties which are impossible to accomplish. The goal of the issuer is to say that the final product is not completed, hence, you will not receive a payment at all.
I think establishing milestones would help to some extent, especially for organizations with low-med reputation.
But, yes from a position of a developer that has received bounties from Ceramic, Badger, Parsiq and Reflexer, I am for this proposal.