[welterde]

Windows actually used to have 6to4 setup by default in the past. There is no need to manually configure anything since the 6to4 have a globally unique anycast address and the ipv6 space is just derived from the own IP address. Of course NAT breaks that if used on some box behind the router (also would break your proposal I think?) and there were a few issues with 6to4 (random people running gateways? who deals with abuse?) that lead to the development of 6rd (and which was used by a few fairly large ISPs).