The problem IPv6 is solving isn't a problem today, because the problem IPv6 is solving is no longer workable.
There is not just one problem. IPv4 addresses are a multi-billion dollar market. People now have to compete globally for scarce resources disadvantaging those with less buying power. Priming SPIs for P2P communications is more difficult to infeasible via local NATs and CGNs depending on implementation and configuration. Lack of global addressing denies users the ability to fully participate in the network. 1:N NAT relies on packet mangling and ALGs with exploitable assumptions.
IPv6 was to preserve that end to end connectivity, and not have to do all sorts of hacky workarounds like FTP proxies, port forwarding and other such things like STUN. It was also to make IPSec practical and workable.
But how much of that is true now? You don't see FTP proxies anymore - because PASV mode, but also because no one uses FTP anymore. It's either FTPS, or SFTP (ftp secure, which uses TLS over the FTP connection, breaking the gateway, or secure FTP, a protocol working over SSH).
The last time I checked people still communicate with each other via text, voice, video, games. They exchange files and data. Demanding we only have the ability do these things via third party "clouds" we have to pay to use one way or another is not a proposition I support.
Even if there is a common service for signaling having a data path reliably remain between peers (by SPI priming) is a huge benefit that enables provisioning of services without requiring massive infrastructure investments to proxy data streams between users.
End to end connectivity is broken because no one would consider putting up anything on the Internet without putting it behind a firewall. So all the nasty IPv4 hacks have to be preserved on IPv6.
The fundamental reason for having IPv6 got broken over a decade ago, and people stopped bothering because it had no benefits over what exists now.
The point of IPv6 is restoring the network to a network of peers where everyone has the same opportunities to participate. What exists now is confluence of pervasive surveillance, commercialism gone too far and consequences of lack of E2E connectivity.
That's the reason IPv6 isn't the primary protocol, despite being around for over 3 decades now.
Speak for yourself, most of my traffic is IPv6 and I access all of my systems via IPv6.
Also, IPv6 purists are just nasty to work behind. IPv6 would replace everything you need - no need for DHCP, NAT, etc anymore i IPv6 does it all. Of course, that attitude dismisses why someone might want DHCP, or NAT, and yes, DHCPv6 and NATv6 exist for those reasons, but the purists hated them for existing and for ignoring very real issues for why one might want to have them.
IPv4 and IPv6 are the same shit. Instead of 1:N NAT you now have a SPI that performs the same logical function except in an inherently safer and more capable manner. DHCPv6 is optional and does the same shit DHCP does.
That, and the music and movie industry should be pushing for IPv6 more heavily because it destroys a key argument in the lawsuits - that the person using the IP address is the guilty party. With everything having independent IPv6 addresses, it's far easier to go after the pirates because they're likely the sole user of a computing device with that IP address. Not an entire family behind a single IPv4 address, when you can have every kid's phone having a unique IP so you can sue just the kid.
Every client device I know of uses temporary privacy addresses by default which makes this moot vs IPv4. If you are behind a CGN in which multiple customers of an ISP share the same IP the CGN will almost always keep state via port range mapping to enable disambiguation. The music industry just needs to include a port number in its complaint.
The primary risk is overt and covert mechanisms which maintain state and identify systems and system accounts not the difference between IPv4 and IPv6 which are by default in practice mostly moot.
