I'm suspecting there's a substantial minority of people, maybe even the majority, who want to forget about the trauma of past lives and/or want to experience the thrill of discovery again for the first time. These people would opt to have their mind wiped and memories cleared. To quote Cipher in the Matrix: "I want to remember nothing. NOTHING!"
I'm not one of those people, for the most part, I think. But this isn't an unreasonable position for everyone. What if there are bunch of ISBEs who just want to not remember a thing before they go into the next life?
This doesn't seem like a small issue. If we were to turn off the death traps for everyone, are we forcing those who wish to forget to remember?
Maybe this is a freewill related reason that they can't be turned off easily?
It should be a choice....I would want to remember if not right away then eventually. I wouldn't want them taken away forever and would want to have something trigger my memory so I can unlock them if I choose. Some see forgetting as a gift, but to me, taking our memories away then telling us it's a school is evil. No one gets out either, so if it were something people might want...then let them forget, and I'll remember when I want and leave when I want. They don't give us those choices.
Maybe also, if they remember but wanted to forget, then there could be a procedure to do to forget again. It shouldn't be all that complicated. They have the tech....but the purpose isn't for us to remember...that is the one thing they definitely don't want.