[ktRolster]

It's not dead simple, it just seems that way because the router already comes configured for it. If you had a router already configured with a default firewall, that would seem dead simple, too.

[hueving]

If it comes pre-configured with the same behavior as NAT (no unsolicited ingress), what does that really solve over using NAT?

[Avernar]

When you get multiple devices that require the same inbound ports (game consoles are a good example) you can open the same port for each device.