IMO I think high kicks were never originally part of karate including other southern Chinese kung fu such as wing chun, ngo cho kun or white crane. Kicks for those styles were mostly for attacking lower body from the rib cage area down. The principle and practicality seem to be base on " the closest distant between two angle is a straight line" the hands is closest to the upper body while the feet are closest to the lower body. The role of the feet would probably be: 1. to keep the entire body balance by being firmly rooted to the ground 2. use for tripping and sweeping, attacking low 3. kicks to the stomach or below stomach such as groin area with front kicks 3. round house kicks were mostly targetting the rib cage, thigh and knee area same with side kicks 4. in step kicks to the knees 5. keeping your opponent or attackers off balance 6. Knees are use also to attack the lower body While the feet is attacking the lower body the hands are simulteneously creating a diversion or attacking the upper body such as the head, throat and chest ( sternum area ). Most of this southern styles including karate have concentrated a lot in strengthening the forearm and shin. The forearm not only is it use for blocking but is also use also for injuring an attacking arm or leg while blocking. One of the main natural instinct of a person train or untrain is the natural ability to use their arms to protect themsleves or attack others. That is why great emphasis is put on developing the arms. Base on the traditional forms that I notice in karate, ngo cho, white crane, hung gar, choy li fut or wing chun there is hardly any high kicks? Unlike in northern styles including Korean martial arts they have forms that consist of high kicks. I guess in some degree it is logically because in street fights especially in group fights I notice it has always been the use of the fist, low kicks, stand up ju jit su, the feet are always on the ground moving or running around. I also notice that in many modern sports free style competition such as in MMA or san shou most fighters tend to avoid the use of high kicks because of the high chance of getting taken down or lossing their balance. I wonder is there any historical writtings about high kicks in karate?? So far I have not been successful in finding any writtings about this. I myself train in ngo cho for many years and I have always wonder about high kicks.