This isn't a bad idea, but... I'm skeptical that it'll do much of anything when it comes to decreasing the number of low-quality questions here. It certainly didn't do much for Progse.
As you say, every little bit helps, but in this case it could end up hurting almost as much as it helps.
IMHO, the best reason to turn this on is simply to reduce the amount of confusion and support that unregistered users tend to generate / require. That's not something to ignore - as one of the folks handling support requests, I certainly wouldn't mind seeing fewer of them - but it's also an issue that could be and maybe should be addressed in other ways; if nothing else, it's a separate discussion.
So I'm marking this "deferred" for the time being. Let's try something else first, and see what (if anything) happens as a result. We'll revisit this idea on down the road.
