Respect, also other preparation at the same time. People begin to leak after being dead for a few hours, have to plug up and close some orifices, make sure the eyes stay closed. Also, hospitals don't do anything after death, and many people defecate upon passing.
While I understand your general point, this right here is one of the reasons why I'd strongly prefer cremation for myself. Knowingly subjecting friends and family to this feels... selfish, and probably traumatic for them to boot.