Every technical point of a Taekwondo motion is related to two kinds; One is how to succeed in attack and defence over the opponent's intention, the other is how to make a big power.

It is easy to make a big power that requires much preceeding motions so that cannot succeed to pass over the opponent's defense. Also is it easy to touch the opponent suddenly that he cannot avoid yet only with slight power. Even a little consideration it is easy for you to understand why, and also to understand why it is difficult to get both at once.