> Ironically, IPv6 "just works" totally out of the box, but IPv4 does not.

Not very ironic at all. IPv6's autoconfiguration (through link-local addresses, the Neighbor-Discovery Protocol, etc.) comes from engineers with decades of experience (and frustration) in managing ISP-sized netblocks.

A friend of mine had a similar "issue". He had a modem too new to be on Comcast's approved list so they refused to register it. After plugging it in anyways, IPv4 was filtered to a Comcast captive portal with modem registration instructions but IPv6 stuff worked fine... whoops.