I think the kicks in Wing Chun are enough. It´s much easier to use your hands than to use your feet. Your hand is able to reach your opponent long before your foot. Why take the long way to attack (circle), when there is a much more direct method of attack? If you are using your hands, then your opponent can´t see a kick coming if you have to use it. When you teach Kung Fu, you can fool a lot of people, but not yourself. You can make like a movie and do many complicated movements and kicks, but you only fool yourself as to whether that would work in a real situation of life and death.