No need for something as heavy as what you propose.
How is this even remotely a bad thing? It's trivial to MITM people on unsecured networks - I can't think of a single consumer router that actually does DHCP snooping to prevent it either.
I want to allow anonymous access, but let the traffic be encrypted. Is there a technical reason why this is not implemented?
I'm very sad by the culture (and moreso, the legal necessity) of restricting wireless access. I want to share, and have at times relied on anonymous wifi to help me get home.
http://www.dhs.gov/xlibrary/assets/ns_tic.pdf
It's a national smartcard identity program that Obama admin has been pushing for a while.