I disagree. Directly, yes, the average user doesn't care. But application developers care; peer-to-peer protocols become a lot trickier with IPv4 due to the pervasive deployment of NAT; two machines ostensibly on the Internet can't connect to each other, requiring instead the use of STUN servers, which then requires infrastructure somewhere, or just doing it client-server, or some mix like having "supernodes" (like Skype, prior to MS tearing it out) that route traffic for NAT'd devices.

The ability to actually connect arbitrary devices, I hope, will be something that people will take advantage of. I know for many game servers I set up with siblings, the ability to not need to mess with a router's crappy "port forwarding" would be a welcome change. (Even if I had to mess w/ some local firewall, but that can perhaps be much more tightly integrated or at least, a better UX.)

Yes, but until you have the percentage of overall IPv4 usage down to less than 5%, 10%, or even being generous say 15%, developers will still have to deal with those things (NATs, STUN, TURN, etc) anyway.

IPv6 has been around for almost 20 years now, and is only recently cracking 10% (and I wonder how much of that 10+% is also dual stack). IPv4 sure as hell isn't going away in my lifetime. Who knows, maybe the lifetime of my kids too. What a mess!

Because the quicker we adopt it the better.

The shittiest of routers support it so when you get one from a major internet company you should expect that it has support for an internet protocol which has been out for 18 years.

Doesn't qualify as "inexcusable" for me, sorry.