NAT64 is a temp bolt on and also not the same thing. If I own 1.1.1.1 in v4, that doesn't mean I own some equivalent of 1.1.1.1 in v6. They had router nat64 and relay nat64, both with dealbreaker problems.
You don't exactly need a translation layer. If they just gave me 1.1.1.1:: in v6, anyone migrating v4 to v6 would have the same route to me as before, and other changes like DNS6 could be gradual. Then after v4 is abandoned enough, I can sell 1.1.1.1.2:: to someone or use it instead of NAT.
SLAAC is a good design as a non-default that people who know what they're doing could enable, but a lot of people don't even want public v6 addrs for hosts, they just want NAT/DHCP.
You don't exactly need a translation layer. If they just gave me 1.1.1.1:: in v6, anyone migrating v4 to v6 would have the same route to me as before, and other changes like DNS6 could be gradual. Then after v4 is abandoned enough, I can sell 1.1.1.1.2:: to someone or use it instead of NAT.
SLAAC is a good design as a non-default that people who know what they're doing could enable, but a lot of people don't even want public v6 addrs for hosts, they just want NAT/DHCP.