Re: I think I know why
Yes, the main issue is IPv6 was designed "too early", when the landscape was quite different, when SOHO and true home LANs were almost unheard of, and most networks were carefully look after by skilled pros.
IPv6 is quite "unfriendly" for the casual network admin. Consumer network devices should have better management tools to take care of it, and "shield" most consumers users from the complexity, they can't handle it just like IPv4 just with longer and cumbersome hex addresses to type and use.
Yes, you can still use IPv6 at the external interface only, and keep on NATting it to internal IPv4 addresses and remove much of the complexity (albeit with the same issues of NAT for some protocols), but that's not what the industry want, I guess, especially since they see a delicious opportunity to track each single device on the internet.