Have you heard of the Jevons paradox https://en.wikipedia.org/wiki/Jevons_paradox? It is really insightful. If you make something more efficient/ easier to use, people will use more of it. That is exactly what I think about the switch from IPv4 -> IPv6. Networking is really complicated now and if you happen to make it just a bit easier and cheaper, people will use it and the related services more.

Stateful NAT is a real burden on bigger networks and is at least a chore on smaller networks. It at least doubles the complexity of managing a network especially when you have a DMZ that should be used from some "private" and some "public" endpoints.

Sure there is. AWS has a vested interest in the value of IPv4 going down as much as possible.

Owning IPv4 addresses is a requirement of AWS’s core business. Unless people stop using IPv4, then AWS cannot sell those addresses. There is no incentive for the addresses to increase in value.

Further, if people continue to use IPv4, then AWS has to continue to acquire even more IPv4, and AWS wants the price of those to go down so that acquiring them is cheaper (or wants people to stop using IPv4 so that they can stop spending money on them altogether).