Good idea!
For two related, but orthogonal reasons:
Stack Overflow needs to be able to have it's own community identity separate from Stack Exchange.
Stack Exchange need to have an organ for communicating to the entire network that is not tied to Stack Overflow in particular.
Stack Overflow's identity
At this point, SO is like a good-sized city. A great city needs a great newspaper. The New York Times, Washington Post, and LA Times are great sources of news, but to really meet me where I live, I still read the Burbank Leader. Stack Overflow needs an outlet for local news: tags to visit, crime reports, editorials, feel-good stories, etc.
The community was formed out of two great blogs that focused on programmers. At this point, the founding blogs have returned to their original programming and the Stack Exchange blog mostly focuses on, well, Stack Exchange or Meta stuff. That's fine, but it leaves a hole in the SO community. MSO covers some of that need, but there should a place for SO's great programmers to wax poetic about programming without needing to conform to a strict Q&A format. Writing a blog might give contributors a sense of agency that writing a meta-post (a "most") can't.
Clear Stack Exchange communication

I like the new Community Bulletin, but it's easy to start ignoring it if there's too much irrelevant information. As I make my rounds on Stack Exchange sites that are not Stack Overflow, I keep running into notices of some sort of election. It's particularly distracting on Biblical Hermeneutics where I happen to have been appointed a moderator Pro Tempore. (Internal monologue: "Let's see what's up with BH. Moderator Election! I'm not ready! Oh. It's just SO. I guess I better ignore sidebar...") Something like 9 out of 10 SE blog posts are relevant to our sites, however, so it would be really helpful to continue having them posted.
But any item that's just about Stack Overflow will either be confusing or annoying to those who no longer frequent the site or have never heard of it. Stack Overflow is awesome, but its awesomeness doesn't need to spill over the rest of the network all the time.