Inspired by your comment, I'll make my point more graphically: Nazi camps were also suitable for medical and spychological testing. Nazi and even interned doctors did all sorts of experiments on prisoners. And if they refused to do so, pretty sure other people would have been happy to replace. Not everyone shared the same concerns regarding human life.
It depends how you see things. imho some things are intrinsically wrong, doing them because "someone else would have lined up to take advantage of the opportunities" doesn't change the fact that it's wrong in the first place.
Just the same way that if something wrong is done by a lot of people it doesn't make it right (smoking, drinking &c.).
Inspired by your comment, I'll make my point more graphically: Nazi camps were also suitable for medical and spychological testing. Nazi and even interned doctors did all sorts of experiments on prisoners. And if they refused to do so, pretty sure other people would have been happy to replace. Not everyone shared the same concerns regarding human life.