I bumped into a few old interesting meta questions/posts: What questions should be compiled into Writers.SE ebook? and Writing Contests. Alternatively, I am also witnessing newer trends and participation in Writing Challenge, Publication Announcements, National Novel Writing contest etc.
After going through all these posts, I think we can actually do more to attract newer audiences (as well as a good amount of readers).
SE newsletters don't include meta posts. Do they? I went here and confirmed this. This means, the fun writing activities like Writing challenges, Contests and Publication announcements that happen on meta don't totally reach out in emails and subscribers. I don't know the number and extent of newsletter subscribers for this site, but I feel that it might not be encouraging more and newer audiences.
Having said that, I propose to re-start e-book publishing (I don't know the status of e-book now) which involves not only great questions of the main site, but also the fun activities happening for writers on meta. Meta is/was not used this way in other sites and since Writing proudly uses it as a part of Writers' participation (PS: see only the comments of the linked answer) and sites' all-round development, we can give it a try. We might start a blog. (If there is none yet?)