I have a feeling that the "Beta state" of the site itself is holding us back. This is not a big deal for programmers, as it's a known concept to them. But for non-programmers, it's more likely to give a perception of "not serious" and "unfinished". In my view this gives the wrong impression as the StackExchange engine is in no way an unfinished product. It's a well-tuned engine that works perfect in every aspect of what it's intended for.
So my wish for a while has been to give the site a "released" look although still in beta. It is not unheard of, as the UX site did get it's finished theme while still in beta, but with the word "beta" still visible in the logo. I think a better look with a more "musical" GUI theme will attract more new "non-programmer" users.
The site has been around for a long time, and it is still growing, although not enough in all the aspects that would tip us over to full graduation. But enough to prove that the site is here to stay.