If such questions are way too far afield, they'll get downvoted enough to be closed.
We really can loosen the parameters for questions quite a bit with that failsafe in place. And we should.
Let's look at costs/benefits for this case: questions that are not strictly confined to Judaism itself.
Potential benefits of excluding these questions:
--We'll have a site that is very organized and elegant insofar as it has theoretically well-defined limits for the scope of questions.
--Oh, and the site will be more appealing to "experts." (Not making fun of you @ShmuelBrin; it really is [the only?] valid point.)
Potential drawbacks of excluding these questions:
--Alienates non-educated and non-Jewish people who would like to ask about Yiddishkeit here.
That is truly a high cost, both for the site and for the world.
In my mind, there is no contest whatsoever.
Anyway, is Mi Yodeya really suffering from a surfeit of questions and posters right now?
Something tells me it isn't. Until that's the case, let's allow in all manner of reasonable questions that are asked with acceptable style and good faith.