Video chat. File transfers without a third party host. Cell phones almost always only offer a public address over v6. Internet gaming. VPNs without address conflicts. Not being banned from Wikipedia because someone else with the same CGNAT ISP got banned.
For the average consumer they don't notice a difference. Both my home and mobile ISPs have said they have no plans to offer IPv6 connectivity because it's not a requirement.
Users don't care, and until a lot of them do ISPs won't do anything.
People can still video chat, play games and use VPNs without v6.
Part of why video chat quality sucks is because the RTP traffic has to be sent through a proxy to deal with NAT, doubling load on the Internet and increasing latency.