I think that these questions just can't be answered, they just provoke a discussion, because the true answer isn't known.
Try hard to differentiate here between:
Questions that cannot be answered (because, for instance, they're asking folks to predict the future or are based on an under-specified and/or completely hypothetical scenario). These should generally just be shut down - discussing them produces nothing but speculation.
Questions where the answer is obscure or difficult to obtain (relies on knowledge in an author's private journal, protected by a non-disclosure agreement, guarded by a dragon). These can be ok, if folks are disciplined about not answering when they don't have access to information. If they degenerate into idle speculation, they should be shut down as with #1.
Questions where the answer is irrelevant and the asker simply wants to get to know other members of the site better by getting folks to post their feelings (this is often the actual case for instances of #1 and #2, but some questions are explicitly asked for this reason). These should generally be shut down - they are discussion for the sake of discussion, and there are other venues more appropriate for this.
The fact is, this is a Q&A website - which means for every Question, there must be an Answer. Folks visiting a year from now aren't going to care about some impromptu fan-fiction you and someone else put together in lieu of an actual answer - if they're searching for a question here to satisfy their curiousity or settle an argument, they're gonna want something substantial, and if we can't offer that we're just wasting their time.
The FAQ states this pretty clearly:
If your motivation for asking the question is “I would like to participate in a discussion about ______”, then you should not be asking here. However, if your motivation is “I would like others to explain ______ to me”, then you are probably OK. (Discussions are of course welcome in our real time web chat.)
To prevent your question from being flagged and possibly removed, avoid asking subjective questions where …
- every answer is equally valid: “What’s your favorite ______?”
- your answer is provided along with the question, and you expect more answers: “I use ______ for ______, what do you use?”
- there is no actual problem to be solved: “I’m curious if other people feel like I do.”
- we are being asked an open-ended, hypothetical question: “What if ______ happened?”
- it is a rant disguised as a question: “______ sucks, am I right?”