I have a associate teaching license in a koryu style (daitoryu aikijujitsu) that I received in Japan. The koryu martial arts community is interesting because many of them see themselves as martial arts historians. They are preserving the techniques exactly as they have been done for hundreds of years. Personally, even though I studied koryu, I think this is not accurate. Martial techniques are organic and even if we think we are studiously copying the techniques of our teachers, there tends to be a drift. Sometimes we improve the techniques. Sometimes we never hit it as sweet as sensei did. Whatever happens understanding changes. It has too. The koryu guys are playing a centuries old game of "whisper into the ear down a line." The end result will always be different.
I have been very interested in the slow morphing of Tomiki kata in the 30 years since the death of Mr Tomiki. Every artist and every organization is pulling the katas in different directions. It has stayed very true in appearance to the original linear look and feel in some groups. In others it has morphed into circles. The ideas about timings, throw angles and connections seem to change radically too. Some groups are proactive, some reactive. Some enjoy rough housing while others are militant about the pursuit of softness. Many Tomiki societies are even including foot sweeps, which Tomiki Sensei had chosen to leave out of the system.
I believe kata should evolve. Mr Tomiki gave us a framework to help us wrap our heads around the principles of aikido. If we become artists we can use his table of aiki elements he proposed and paint with them throughout our aikido careers. The techniques are a palate to paint the canvas of the mats.
No great artist paints the same thing through their entire life. Artists go through movements. Perhaps Picasso's blue period is equivalent to Tomiki Sensei's competitive Judo days. Eventually in both artists the motivations that caused these movements passed and they went on to create in new ways.
I humbly submit we should closely look at and study the kata and techniques of our teachers, all the while painting something new with our own understanding of the glorious flow that is aiki. Aiki is not something that can be copied. It must be created.