It's an interesting idea. It would definitely have to be opt in.
My first thought is that, having run a couple of magazines, it's a surprising amount of work to do, even for a page or two. My second thought is that pretty much all of what could appear in a newsletter can appear here. My third thought it that, while you're right that it could reach a lot more people, the people who don't participate here that frequently probably do so out of choice, so they probably wouldn't opt in anyway.
But those are just my thoughts. I'd be interested in hearing what other people think.