There is a huge difference between an actual murderer and a fictional character, one killed real people and one didn't exist and therefore killed no one.
I personally find it rather sad that the victims are being dismissed because of their profession and that somehow they were better off dying at the hands of a piece of crap rather than whatever end fate had in mind for them. Prostitute or not, they didn't deserve to be murdered for some freak's jollies. I also don't understand the reference to him as a 'romantic villain'. Murderers should never be seen as romantic. People are defined by their actions, and his actions should only get him labeled as the filth he was. In my opinion, elevating his status as a cult figure is a slap in the face to his victims and gives him exactly what he sought. The only consolation is that he remains anonymous and that he never got the satisfaction of being immortalized personally.
Collect what you want, but I don't understand why you would want a representation of someone who did such despicable things to innocent human beings hanging in your house.