I'm the guy who asked "What is the Great Attractor?" and I admit that I pretty much knew the general answer before I asked it. I asked it at least partly because I thought it would help the Astronomy SE become more ubiquitous. I kind of know how Google works (I used Google ad-words in my business and have done a little work in SEO), and I know that a lot of StackOverflow's traffic comes in via Google searches, so the more hits the Astronomy SE gets on Google (or, for that matter, Bing), the greater will be the knowledge of its existence, its usage will go up, and everyone will benefit.
Keith's "Con" above is actually the point -- we should be trying our best to get Google to point to Astronomy SE in addition to, or even in preference to, other sources that might have an answer. Including Wikipedia. Note that if we reference Wikipedia in our answers, this will actually help Wikpedia, not this SE, per se. But if this site becomes a source of references for Wikipedia articles on astronomy, this will benefit the Astronomy SE. Note that Google increases the score of sites which are referenced by other sites. By becoming a source, our rank on Google goes up, which is to be desired.
Keith is right that it is important to build up a pool of good questions. Good questions include not just the esoteric, but also the basic. If you search StackOverflow for "What is recursion?" you will find that this basic question has been asked, and has been answered, not closed. OK, marked as a duplicate, but not closed, and with some good answers and a few programming jokes thrown in. In my opinion, SO benefits from this question having been asked. And if you Bing "What is recursion?" this question on SO is #8 in the list of results.
Another case in point is "What is tail-recursion?", which is a very popular question (viewed nearly 100,000 times) with 396 upvotes and has been favorited 179 times.
The point I am trying to make is that we should be making a goal of turning this Stack Exchange into an important resource for people to find out more about astronomy, and one way to do so is to serve all levels, from basic to advanced to esoteric. If someone Googles "barlow lens" for example, we should want this SE to be high in the search results. This increases the size of our community, because the more people who come here and ask questions without being shunned because they can find answers somewhere else, the better.