The original way the Exoskeleton was pitched by Elon was as a replacement for the traditional truck ladder frame, which he described as dead weight. So the implied concept was that the outside of the Cybertruck would somehow carry the weight of the truck, instead of the ladder frame on the bottom of a traditional truck. Now we know this not the case, the Gigacasting is what carries the weight of the Cybertruck, and to some extend the battery pack does that as well. But the exterior panels certainly do not. Just because they withstand the force of your foot doesn't make them an Exoskeleton. A tough layer of skin, sure. But not Exoskeleton or any other word containing the root "skeleton."