Now, specifically concerning the completeness. Yes, I believe that in many case we would have to wait too long. Let me give an example. I am a professional scientist, specializing on nanoscale physics. You know, acquainted with Nobel prize winners and so on. I know for sure that if we talk about the article, say, "Andreev reflection", there are 100 to may be 500 persons in the world, myself included, able to create a reasonable quality Wikipedia article on the subject. Most likely none of them is a Wikipedian and none of them will ever create such an article. (The article exists now on en.wp as a stub). We can wait of course till the number grows to 1500 and hope that some of them suddenly turn to Wikipedia (do not forget that most of them are active researchers who do not have time for hobbies). There are three different approaches to this problem, as I see it. 1) To approach individual experts and ask them to create an article (top-down approach). 2) To see when someone creates a stub and then approach to these experts and ask to referee the article and to help with building up the structure (bottom-up approach). 3) To rise the Wikipedia status to such a way that creation of say an FA would be equated in status to publishing in Nature (the most prestigious scientific journal). Then people would do it themselves. The #3 way is of course the most desirable, but not very much dependent on us in a direct way.
I will comment later today about flagged revisions too.