I guess you are right. I am not a fan so never bought it and never got the free version.
But TF2 is not abandonware, in that respect I think people who paid full price for it should get a free code to unlock something special in the game itself.
But hey that's just my view.
and if you can stretch the definition a bit more, Fallout 3 and NV, both Mass effects, GTAIV, Mafia II and Just Cause 2.