I think, on reflection, that I'm with Aitch and Millyr. I think children need to be educated about the Holocaust, and perhaps visiting a Camp is a way of making that education 'real' to them.
DH has Jewish blood in him through his mother and his Grandmother's first husband died in the camps. However, he doesn't want to go and see the camps, and he thinks it's well, if not ghoulish, then a bit distasteful for someone with no connection to go and wander around what is a mass grave/murder machine for the sake of distraction. On the other hand, everyone has their own reasons for going and if you wanted to see where your relatives had been, I do understand that impulse and YWNBU to want to visit.
I can't understand anyone with no connection to it wanting to go, though. DH went on a stag do in Estonia a few years ago and, insanely, as part of their itinery they were offered a trip to a camp. That WAS ghoulish - they all refused (went go-karting instead), but if that's how it's being marketed, you can see why people would find it distasteful. I don't think the camps should be demolished, however.
On a personal note, my theatre group put on a play last year, Kindertransport, which deals with the Holocaust and the aftermath, and I played the mother of a child who is sent to England, who herself ends up in a camp but survives and returns to find her daughter, who no longer wants to know her. We were asked to perform it again as part of Holocaust Memorial week for an audience of survivors and families who had been affected by the Holocaust and the Transport. Even thinking about it now makes me well up, doing that was incredibly traumatic and although it 'needed' to be done, I would run a mile from doing anything else associated with the Holocaust because of how it affected me. I certainly couldn't bear to then go and visit a place where such evil took place, I know I would find it too harrowing.