Well over the centuries the kata forms movements have changed, no longer truly representing the form of what is really happening. And kata has been intentionally changed.Not just as creative dance, but also as dynamic meditation. Yet by making up your own Kata, your making a statement that you have learned and are practicing techniques that you have proven in a life and death street fight or actual hand to hand combat situation, not in a ring or tournament.
Those classical kata's that you learn are from actual proven fighting techniques.
Choki motobu (one real bad karateka) only practiced one kata... He put more emphasis on kumite. At 52 he signed up for a competition against a western boxer and won.