Dispite a lot being made of the gekisai being created to build stronger minds and bodies during the period of the Japanese military build up, I think this may have actually been a clever marketing ploy by Miyagi Sensei to give his new kata more credibility with the Japanese, and particularly with the dai nippon butokukai. His main priority was to inspire interest in the classical kata.
Before gekisai, practise for a beginner would consist of junbi undo, hojo undo and sanchin. A student wouldn’t even touch a classical kata for a very long time, and even then the student would only be taught one or two at the most. Miyagi Sensei was concerned because most students would leave through boredom, and it became apparent that interest in karate was not very high among the youth of Okinawa. Miyagi Sensei wanted to create promotional kata to create an initial interest in karate during the formulative years, which could then be built further upon once that interest had blossomed. The promotional kata would be easier and quicker to learn, and a student could see their progress faster and get less disheartend than with the older teaching methods.
Much of Miyagi Sensei’s reasoning can be seen in the transcript of the 1936 meeting of the masters (Ancient Okinawan Martial Arts Vol 2 – Patrick McCarthy). Miyagi Sensei says ‘Concerning kata, perhaps it is better to develop and introduce a national kata, although the classical kata must remain. Suitable kata with both the offensive and defensive, for students from elementary school to university level should be developed’.
The techniques used in the gekisai kata, ultimately are taken from the classical kata and so still have purpose and martial value. The kata also include the use of age uke and jodan tsuki which do not appear elsewhere in the kata of gojuryu, and can be considered a nod in the direction of shorin ryu.