I do believe that more discussion of which kinds of top-level posts and which attitudes in the comment stream encourage or discourage participation could fix that.
We should talk about this. We should also just write an FAQ. We don't need to postpone the latter for the former.
What we are planning is, by the way, not literally an FAQ. The Lurkers thread didn't reveal frequent questions people had that we're not answering, or that they have trouble finding the answers to.
The Lurkers aren't who the FAQ is for- if they've been lurking a while they've probably figured a lot out. But when new users show up who haven't been lurking the same topics have come up repeatedly.
Less Wrong is extremely intimidating to newcomers and as pointed out by Academian something that would help is a document in FAQ form intended for newcomers. Later we can decide how to best deliver that document to new Less Wrongers, but for now we can edit the existing (narrow) FAQ to make the site less scary and the standards more evident.
Go ahead and make bold edits to the FAQ wiki page or use this post to discuss possible FAQs and answers in agonizing detail.