That's due to how they handle gear in this game. Our characters are essentially legos - our feet and legs are separated and get swapped out whenever we equip something new and "pop in" together to form our character models. For them to create stockings that go farther than the ankles, they'd need to create a piece of feet gear that "continues" it; while wearing anything else than the "continued" footwear would return you to the 'abrupt end' issue. or they could make a leg piece that occupies both the feet & leg slots - but you'd give up your choice of footwear.