I don't think that this issue is as important as others who have commented/answered, and I don't think any changes are necessary, as the situation resolves itself the vast majority of the time.
1- The original poster (OP) has solved the problem, or at least thinks it is solved.
2- The community has indicated what it thinks is the best answer through the voting. Quite likely the community has also (in comments) indicated problems with the accepted answer.
3- The Googler (or Binger!) who lands on the question page will see the accepted answer, the community-voted best answer, and quite possibly a number of other answers, and so presumably has the tools to solve their problem.
4- It is dangerous (and arrogant) to not accept the possibility that the community could be wrong and the OP and writer of the accepted answer correct.
I do not think the community should be able to "unaccept" an accepted answer through downvoting. I suppose a moderator could be given "unaccept" authority, but that concerns me too because moderation on these forums is at times heavy-handed.