Re: Reason for disabling IVP6
"so machines on your LAN can have an actual WAN-visible address of their own without needing a trick like NAT."
Avoiding that configuration is exactly the use case for using NAT with IPv6. As others have pointed out, you can accomplish the same thing with IPv6 router configuration, but NAT is easier in terms of configuration and maintenance. Given that, and assuming that you don't want to be able to have arbitrary machines open ports that are visible to the internet, then why not use NAT?
Also, if your goal is to make people more likely to move to IPv6, pointing out IPv4 methods that will work with IPv6 (even if you don't consider them optimal) seems like a really, really good idea. It eases the transition.