Just curious. Isnt one of the reasons for kata to train the mind? Hypothetically speaking, if by studying the kata you correlate a relationship with current BJJ ground fighting(or whatever ground style) isnt that just a deeper mental aspect of training the kata? Therefor, it is karate? Even though it may or may not have been around originally in the kata or before 1991, the relation allows you to remember the technique with the kata?
Why is everyone afraid to make a new kata with ground fighting? Isnt that what most Karate of the past did? Itosu with pinans ,maybe even kankudai and bassai sho, ive read rumors of him altering and creating naihanchi nidan&sandan. Funakoshi, Kyan, Shimabuku, etc.. all altered their katas and karate practices to fit their needs & views.
Adding ground fighting you learn from somewhere else only adds to your karate and how important your kata is. Which is why I like the term crosstrain... im training with people that emphasize aspects I normally wouldnt. Mixed martial art gives the impression that once you mix the styles they somehow remain independent of eachother, but in reality you are just creating your style.
Sometimes I wonder if you can get too caught up with what it was or should be, instead of what it is or could be.
If I created a kata which movements and applications had no meaning, it looked good but you didnt understand the movements. Scientifically speaking, everything is good.. positioning, structure, etc.. but no meaning. By way of studying the movements you discover combative elements... its original intention really doesnt matter because it works, the point im making.. isnt the mental stimulus of the kata the most important aspect?