they aren't only for installing the heatsink. Those feet are there to prevent "rolling" or the heatsink wiggling from side to side when the computer is moved or you're working inside the computer and touch the heatsink or even anything that puts force on the heatsink. When the heatsink 'rolls' it puts pressure unevenlly on the core, and can do a bit of damage. Those feet prevent the heatsink from moving.