It's not just NAT traversal. Having a flat naming scheme and every entity directly addressable is one hell of a feature.
When I describe Tor to interested techies, I explain that a .onion address is more akin to a phone number. You don't have to know what IP4/6 the endpoint is. You don't have to know the route path. You just need the "dialing address" - the .onion . I find that this description gets away from the whole "Tor is just for drugs and child porn".
And no matter what's in between, if you send data to ###.onion , it either completes successfully or doesnt. And with the system modification I recommend elsewhere on this article, you can even set up Puppet, Ansible, MQTT, and more all over Tor.
I particularly like that you mentioned "NAT Traversal" as one of the benefits of hidden services.
I think that's an overlooked feature that would in many cases be enough of a reason for one to use them, even without caring for the added privacy.