Part of the reason we don't just map IPV4 space into IPv6 space, I recall reading, sensibly, was that it would make routing a mess, and potentially even get messier.<p>The idea was to re-issue address space in a more coherent manner to make things easier to manage at the peering level.... which seems sensible.<p>It also a mistake to think of the internet you see today as "Designed".... the protocols were designed, but the particular way we use them, the parts we didn't use, and the way the internet grew as it did was organic, not pre-planned. To expect some people to get together and come up for a rock solid plan to migrate all that to IPv6 is to ask for something completely unprecedented.
The tools need to be there to allow for organic adoption and growth.... and nobody should be "selling" ipv6 addresses.... there are more than enough to go around, that was the whole point. IP address space was never intended to be monetized.