I agree that with showing nudity in Schindler's List, Spielberg tried to present a realistic account of the atrocities committed by the Germans in Auschwitz. It is clearly not pornographic - but we have to be aware of the sad fact that there are people who might feel thrilled at the sight of such pictures. This is unsavoury - but it happens and every filmmaker knows these effects and has to weigh the pros and cons of showing such pictures very carefully. I think that Spielberg did his very best!
Those who wrote that art is about beauty are wrong - art is not necessarily about beauty. On the contrary, some of the best works of art present and reveal the dark and repellent sides of life, imagination, and humankind - such as Goya's Los Caprichos which are definetely art but aren't beautiful at all. They are not meant to be beautiful. Art is about strong reactions - be it bliss or disgust.
The problem with Schindler's List is that it cannot, like all art concerned with the Holocaust, do its subject justice - that is impossible. The Holocaust in a way is indescribable. All art that deals with the Holocaust can only be an approach or approximation to the horror that took place. And as such I understand Spielberg's attempt to show the vulnerability of humans who are 'allotted' to be 'extinguished' by showing them naked in front of cruel, fully dressed 'Herrenmenschen'. That was an artistic decision, even if the scene was consistent with the actual events.
But in the end, it's nothing but a harrowing, terrifying picture - something we will never be able to imagine despite the movie's attempt to be realistic - but Spielberg gives an idea of it and that's
his meritoriousness.