So called hostile design in fact reduces the incidence of confrontations between police officers and trespassers. Since it reduces the incidence of confrontations, and therefore violence, I think comparing it to "cracking skulls" is unwarranted.
If a private property owner has trouble with people loitering or sleeping on their property, what options do they have? Call the police or hire a security guard, who will use [threats of] violence to solve your problem. Or using "hostile design" that non-violently but clearly communicates the desires of the property owner, thus avoiding any potentially lethal confrontation.
It seems obvious to me that "hostile" design is in fact the humanitarian approach.