By now I'm semi-convinced ISPs are deliberately holding back IPv6 in order to make a buck selling static IPs. They charge a good chunk of money per month for an IPv4 address (at least in Switzerland, the UK, and New Zealand), which is basically just rent extraction from artificial scarcity. And it's pretty obvious that once they transition to IPv6 there is no good reason not to give every single customer enough static IPs for a lifetime of devices.