The worst teacher I've ever seen had an MA; one of the best had never been to university at all. David Cameron's latest gimmick to appeal to middle class parents - devised no doubt by a bunch of people who've barely set foot in a classroom since they left their expensive, fee-paying schools - doesn't wash (and I got a 2:1, so I would've made the cut).
What makes a good teacher? The ability to teach.
The real crime of a poor-quality university degree is this: we're encouraging millions of people to stay in education, loading them with debt on the premise that they'll eventually land a high-paying graduate career and then spewing them out into the kind of jobs they could've got by leaving school at 16. Sort that one out, someone, and you'll be doing something worthwhile.