Comment by MPSimmons

>The whole premise of IPv6 is that every device should have a globally routable IP

I would agree with the small adjustment of, 'every device should be able to have a globally routable IP'.

There are a lot of devices, like the ones we're talking about, that should not be accessible to the internet at large. You're not preventing them from getting a public IP because you don't have enough, you're preventing them from having a public IP as part of the belt-and-suspenders approach because there's no need to have one.