For my piece, I think the most important part is alerting the potential "helpers" to the fact that the poster has a "below acceptable" accept percentage is the real way to go.
From my own experience on less than 1 month usage, I have seen several posters (who stared off with a reputation rating above my own) repeatedly ignore answers that were given. In the worst cases, either:
So while I agree that other factors such as up-voting responses, and even general commentary around why a response if not the accepted answer, may and should be taken into consideration, I do believe that in the good nature of a knowledge base and the rewards system that is the core of the principles here, that the behaviour of non-acceptance should be very strongly discouraged.
As such, it should be a "name and shame" flag that is present on every post submitted by such a poster until the acceptance level tolerance is resolved.
It does not help the spirit of these sites if people are continually allowed to selfishly leach from those good people who are willing to spend their unpaid time and effort to help.
We ask for only one small reward. Acceptance. Please make this a Feature.