You're right, I did forget that. That retcon first appeared in the late 70s/early 80s, I think. I wasn't reading a lot of DC back then, so I'm not sure. But, one of my favorite stories featuring those heroes was "The Golden Age", by James Robinson and Paul Smith, which appeared in 1993-94. The theme of heroes being forced to obtain government sanction or retire was central to the plot of that GN.
Any comic with Hitler as the main bad guy is going to be great.