Comment by mikkupikku

With IPv4, if NAT isn't working right then I simply cannot get online and I need to fix it. Fail safe. With IPv6, when my computers being globally addressable is the norm, if my firewall is misconfigured my computers will probably still be online. Fail unsafe.

Arguing this is pointless anyway because it's not even my decision, it's my ISP. I am however quite happy with my ISP's choices in this regard.