Martial arts change because times and requirements change. Tae Kwon Do now is not the same as it was 30-40 years ago, for the most part. Tae Kwon Do years ago was designed to save your life, make you a stronger person, and help defend the Korean nation. As a result, technique and thinking was geared toward power and strong concentration. The tournament mindset prevalent today has resulted in necessary changes in thinking as pertaining to how technique is executed and your mindset.
You cannot effectively win tournaments if your technique is designed, and you train, to focus power and defend yourself. If you want to be a tournament champion, you must change your technique and thinking to reflect your goals. If you are not interested in tournaments, or not serious about them, there is no need to change, and you can continue to practice traditional martial arts.
Even within our organization, technique is executed in different ways, depending on the teaching styles of the Instructors. Some students are more tournament oriented, and this is reflected in their technique and fighting style. Others are more traditional, and their technique and power show this.