Insensitive to the victim's family, yes. Insensitive to you or other reading this with no connection to the victims, why?
It is what it is: a skeleton, a body etc. Even to people of religion, the person ceased to be a person upon death.
I agree with you that the house will (at least for a time) hold less value. But the reasons for that are, I'm afraid, down to hocus pocus... There is no rational reason for the present or future owners to feel uncomfortable living in that house other than, as you said, tourists such as Villa's Martin O'Neil (I'm not joking either). That's the only reason why I wouldn't want to live there. Anyway, the tourists will find something else to interest themselves with.