This article (Dai and Shō in Kata) recently shared on the Motobu-Ryu Facebook page and website briefly discusses Itosu's modifications to several antique forms, namely Kusanku and Passai. The Kodoryu group researches and preserves the original functions of the antique kata (forms inherited in Okinawa from China). Keeping this approach to kata in mind the article raises several questions.
Why did Itosu modify the kata? Kusanku and Passai had an original function and purpose, by changing the kata or 'modifying' them what is encoded in the movements becomes obscured or worse completely lost. There is no explanation or information from Itosu himself discussing the original functions of the forms and what benefit changing them has brought to the kata. Did Itosu know what was originally intended for the katas Kusanku and Passai? or did he inherit only the sequences? without the kata functions Itosu was free to alter the forms as he pleased.
Itosu's modifications to kata can in some ways be seen as the starting point (or deviation?) for the modern approach to kata, defined as 'creative interpretation'. Once the form has been altered and the function lost the disconnected sequence can be interpreted however anyone chooses as we see today with instructors creating endless applications for all the 'versions' of kata across the different styles of Karate. Creatively interpreted Karate and kata has separated itself from the original functions of the antique forms and become something quite different. What if Itosu had known the original functions of Kusanku and Passai, would there have been a need for Dai and Sho 'versions' or the restructuring of kata?