I don't think you're grasping my argument at all. Moving it to 15 and getting rid of the additional rewards isn't in any way a happy medium. Moving it to 15 is irrelevant; the difference is between having all of the vote value given to the post, and having some of the vote value senselessly trashed.
A happy medium would be giving the additional rewards to the successful curators instead of the author.
The closer the 30 gets to 0, the more it goes towards paying curators the "full" 25% regardless of when they vote.