I too, am from the no port forwarding school in order to make the basics work.

If what you all say is true, then we would all have to use DMZ and forwarding, etc.
I don't choose to use the ATA or my DSL modem, for that matter, to do any other functions than I believe it to be designed to do. I have a router for PPPoE as well as routing for my VOIP ATA.
I think that when these isolated problems occur, they are as a result of mis-management on the users setup, and these work-arounds should only be necessary in rare cases when a diagnosis is not available or perhaps when there are esoteric setups that fall outside the realm of provider supplied and provisioned ATAs. This may even extend to unique arrangements with the users ISPs as well.
Just my opinion...