Basically every horror movie since this has been “inspired” by the Tate Murders. Real
Life events lead to horror movie subjects which is why I can’t look at a movie at being exploitative. Hostel was made from real life events, Nightmare on Elm Street, Jason, etc. if that’s the case, then every serial killer/murder movie type horror could be considered offensive or tacky. I’m not going to stop watching Rec or Quarantine bc of the Covid situation which would be equivalent to your rationale. Recently, the movie Host and the “Lyft driver from hell movie” those are based off incidents. Where I draw a discerning line is children. I don’t like the concept of kid victims for display in horror so I’m very avid about how that’s portrayed.
You are misunderstanding my point because I am not saying real life events can't used as fodder for film/TV
The Manson stuff is imprinted on the US cultural psyche and has been for 40 years. It's different than whatever obscure real life event inspired those other horror movies you mentioned. The Texas Chainsaw Massacre was inspired by Ed Gein but it didn't depict Mary Hogan or Bernice Worden (Gein victims) as characters in the movie.
Abigail Folger, Wojciech Frykowski, Steven Parent, Jay Sebring, and Sharon Tate (and her unborn child) were all real living breathing people who were brutally murdered that night. They used their real names in this movie. Nothing was inspired about that, they tried to walk the line between docu-drama and horror movie and failed at it.
They have families and friends who are still alive to this day and with that knowledge it requires a more deft touch when using that as a basis for a movie. The people who made WOLVES AT THE DOOR were sorely lacking in that respect. They just made a mediocre home invasion horror movie.
An instance of using real life events and people as characters in a project is the Netflix show MANHUNTERS that does an amazing job mixing real life serial killers and their victims with made up characters to create a fascinating thriller series. They did it well while WOLVES AT THE DOOR is just forgettable tripe.