When a book is banned, buy that banned book. Whether you agree with its contents or not. Human history is not to be erased.
That aside, I've been in the kink circles, I've been in enough relationships. Hell, when I was a kid my babysitter would watch cheesy lifetime SA stories to trip her lust trigger. The vast majority of people understand fantasy from reality and have an interest in fantasy. Some even use it as a control mechanism to deal with past traumas. I as an individual don't enjoy many of the kinks of some partners I've had - choking, slapping, degrading. pain play, ice play, and countless others. Not my thing... but many of them have asked for these things, and with a safeword in place, I've obliged.
Just because you don't appreciate a work doesn't mean it is valueless. Perhaps viewing it from a negative view is what provides it value, standing as a testament to the dark side of humanity that one should avoid.
We can't hide in our holes and say that evil doesn't exist. To truly understand something you sometimes need to roleplay its scenarios to recognize it fully. It is better that people do so in a safe environment, away from reality. Finally, the rights of the people do not end where your fear begins. Freedom is a scary thing, and the world is a scary place.
To quote Star Trek's Q, "It's wondrous, with treasures to satiate desires both subtle and gross... but it's not for the timid."