The reason why they show the naked prisoners is to try to demonstrate how the Nazis had reduced these people to subhuman in their own view. By denying them dignity and brutalising their prisoners it made them easier to abuse, torture and kill.

I agree Abu Ghreib does not closely resemble Auschwitz in purpose or by the demographic of its prisoners or gaolers, but the treatment metered out to Iraqi prisoners invites a degree of parallel because the torturers are still treating their charges in a demeaning and violent manner by torturing them. The warning of Auschwitz is this behaviour is NOT tolerable in the civilised world, no matter who has power over who.

If you cannot see THAT, then that is truly very scary.