It isn't that heavier objects (including human bodies) fall faster, it's that their momentum is greater. If you're talking hanging, that means the heavier you are, the more force will be exerted on your head and neck when the rope pulls you up short. It's an important calculation, since the length of a drop that will instantly (and theoretically painlessly) separate one person's brain from their spinal cord, thus bringing a speedy end to both consciousness and life, might cause a lighter person to slowly strangle, and a heavier one to be decapitated entirely.