Don, you make a good point about the front QR only configuration still requiring a wrench to be carried. John Wilson has a great answer too.
The general public is afraid, very afraid of taking off the rear wheel. Even QRs are too hard for many. Hard for us old hands to imagine but it is true.
A man who was buying a bike at my shop years ago was using the bonus money that his engineering team was awarded for finishing a job on time. He had a harder time with the concept of the QR than the average housewife type. I hope he wasn't designing bridges!
A lawyer asked for a QR and a fork; seemed illogical so to better understand what he wanted, I probed further. He was "building a case". At that point, I didn't know he was a lawyer so I assumed a travel case for a bike. When we learned he was building a case against a bike shop (a very famous case as it turns out) we lost interest in helping him. He told us, rather disgustedly that not everyone was a bike nut like us and that some were doctors and such who didn't have time to learn how to use quick releases. I kid you not.
Chuck Hoefer
Vista, California USA