Beneficiaries can be used for two other important purposes; funding the Steem.DAO and reducing the token supply. Because the Steem.DAO is technically just an account on Steem, by setting @steem.dao as a beneficiary on your post, you can send a percentage of the rewards you earn on a post directly to the Steem.DAO to help fund great proposals.
Not a bad idea for people who want to fund the proposals. We need to encourage more ways to reduce the circulating supply of Steem though.