I've seen several meta Questions on the viability of Writers.SE in the Stack Exchange format; I'm hoping this is a good angle to tackle this issue from.
From the Area 51 FAQ:
We want you to capture the moment that plumbers feel when they look at PlumberOverflow and say, "Whoa! That's my kinda site!" On a site about plumbing, there are 200 easy plumbing questions, and they've all been asked 100 times on other sites. Don't suggest questions like "How do I unclog a drain." Instead ask, "If you run 2.5 GPM through 50 feet of 1/2" galv pipe, how many psi will be lost to friction loss?" Remember, the pro sites WILL attract the enthusiasts, but not the other way around!
I think this is a very good description of the sense I've been getting from Writers.SE in the week or so I've been following: lots of questions which address very familiar topics; very very few that seem like they might have been asked by an "expert" in the field. And that might well be the difference between whether the site offers something unique and valuable, or just repeats existing resources in an unusual format.
Would people say this feels like a fair assessment? What questions (from the site, the beta Example Questions, or made up right now) would you consider to qualify as being not only on-topic, but genuinely "expert-level"?
Clarification: The above is not meant to imply the site should have only "expert questions," or even mostly. Only that the presence of some seems important; and that the difficulty I'm having in describing such questions is discouraging to me. And conversely, that any ideas people have on what questions writing experts have for one another would likely be extremely interesting and unusual.