NAT is not a security feature. Your firewall blocks incoming traffic, not NAT. It introduces new complexity that now needs to be solved.
In corpo environments you have to struggle with NAT traversal for VoIP communication.
In home networks “smart” devices attempt to solve it with shit like uPnP and suddenly you get bigger holes in your network security than before. You could find countless home network printers on shodan because of this. Even though (or maybe because) they were “behind” NAT.
Off topic, but I love Hurricane Electric’s website. Simple, but not ugly. Straight to the point. I find it quite charming in contrast to the hyper designed, but barely functional sites of other companies. (fuck you HPE)