I know that with many of the styles of modern Taekwondo as its been practiced for the last fifty years or so they have added in lots of hand strikes but I believe originally when Taekwondo was first being developed it was mostly just kicks with very few hand strikes. The reason for this from what I heard was because the Koreans were skilled craftsmen so they needed their hands for the stuff they would do and so training the hands to be used as weapons could be detrimental to their jobs involving crafts. Much like in the M*A*S*H episode "Oh, How We Danced" where the character Winchester starts learning some kicking techniques.