Comment by unethical_ban

From my readings and limited experience, it's two things.

First, IPv6 in the 90s and 00s is different from IPv6 today. Various extensions and standards have been added that make IPv6 administration easier than it was in the early days. I want to say RDNSS is one of them. Background: one of v6's early selling points was SLAAC, where DHCP could be disposed of and endpoints would auto-configure their own IPs in accordance with the network announced by a router. Problem is, without DHCP, there was no way to get DNS, and DHCPv6 wasn't widely deployed/it was discouraged... so how does one get a DNS server automatically? RDNSS came around to announce DNS servers from the router directly.

TLDR: Early IPv6 sucked more than today.

Second, it's simply a chicken-and-egg problem, particularly at the consumer network level. User-friendly IPv6 router configurations are still rare for home routers, and ISPs have simply dragged their feet. At this point, if we're going to have government mandating all manner of things for consumer products, we should be mandating IPv6 support on home routers and that ISPs delegate at least a /60 to each customer.