In any sport, the winners are determined by those who perform the best under the given rules. In international Taekwondo competition, the rules are determined by the World Taekwondo Federation (WTF). The WTF is controlled by the Koreans. Therefore, international Taekwondo rules are determined by the Koreans. If you do not play by the rules they set, you will not win.
Some think that change is always good and the adherence to traditional ways is passé. Which came first the chicken or the egg? Did the international rules come as a result of improvements in Taekwondo techniques, or did the new techniques come as a result of them being more effective in international rules competition? If you want to be an effective fighter under international rules, then you must use techniques that take advantage of the rules.
This does not mean that traditional Taekwondo practitioners should not make changes as more knowledge is gained about physical training. We now know that traditional deep knee bends and full sit-ups are harmful to the body and should be avoided. We know that Americans get bored easily, so traditional training classes do not spent as much time performing the same technique over and over, as they did in the past.