Consensus seems to be that forced acceptance of answers, which appear valid to others of high reputation, should not happen even when the originator appears to have lost interest.
If that is a given, then I think we should move to allow such questions to be closed with a new value of Originator of question appears to have lost interest.
The guidelines on when to use this might be when the question has had no edits/comments made by the user in over a month, even when comments/answers have been provided and thus appear to be falling on deaf ears.
I'm sure many of us may have neglected following up on our own questions at times, and that these may become subject to closure. However, I would rather have a question I had forgotten about closed than have people working on a solution for it that I and others may never use.
The answer from @whuber got me thinking some more and so I wondered "Do closed questions ever get deleted?" - the Answer from @Jeff Atwood seems to be "sometimes".
Following up on @whuber's "carrot and stick" approach to what we all want, i.e. high quality Questions with high quality (Accepted) Answers, I'm going to make a further suggestion or two. I still don't have a grasp on all the Stack Exchange functions and procedures so I apologise if I go over any old ground.
When the community, by its normal voting practice, thinks a Question should be closed, for any reason, I think there needs to be some penalty on its asker - perhaps loss of Reputation gained for that Question plus 10 more points. Upvoted Answers to such Questions should NOT lose Reputation at the same time. Closed questions can be-reopened (unless they are moved to Deleted by the Moderators) by community voting, which should restore Reputation from the Question (but perhaps not the penalty 10 pts so that we avoid "risk of Closure").
I think I'll stick by my suggestion that "stagnating" questions should be closed but I agree with @whuber that reassessing "rewards and punishment" first may be a better approach to getting high quality Questions with high quality Answers (irrespective of their Acceptance).