Why didn't The sister location animatronics use these guys as a skin suit?

Id say they seem in good enough quality if all they got was hanged, is there any explained reason of why they didn't use these two corpses and instead played mind games to get an alive person?

Id say they seem in good enough quality if all they got was hanged, is there any explained reason of why they didn't use these two corpses and instead played mind games to get an alive person?