I don't have a problem with this behavior per-se. The semantics of a closed question are simply that no further answers will be accepted, because the question is not appropriate for whatever reason. I don't think its primary purpose is punitive, but editorial. In particular, you have to keep in mind that closed questions could be re-opened later. Therefore, nothing drastic should take place; that's what locking and deletion are for.
- I don't see why voting should stop. Sometimes seeing a question's popularity can influence the potential re-open votes. Voting on the answers can have a similar effect, if some truly excellent responses are given to an otherwise marginal question, that might influence the community to re-open the question.
- I don't see why a closed question should not have an accepted answer. Again, it could be re-opened later. I don't see how precluding a question from having an acceptance improves the quality of content on the site. Any question, even a closed one, is potentially (though not necessarily) better for having an accepted answer.
Again, all of this is part of the editorial process. The effect on reputation is secondary, and shouldn't dictate the semantics.