This is well expressed in the Japanese concept of "Hacho": deliberate asymmetry (Lowry, 100). It exists in all Japanese culture, from budo to woodworking. It refers to an intentional informality, amidst all of the formality and attention to detail, to allow personal expression to flourish.
Applying karate to one's own physical being naturally results in a unique and personal way of doing things. The uniqueness is usually subtle, from the slight shift in weight during a body movements, to the hand position in tora guchi, to the path of motion during a shuto uchi. This natural process of individualization must not be supressed for the sake of maintaining consistency within the Ryu, but it must also not be forced or abused. When one adds, removes, or drastically changes movements of a kata and upsets its essence or changes fundamental teachings of the Ryu, it is not Hacho.
This is also well expressed in Shuhari. For those who aren't familiar with the concept: Shu-to learn from the tradition. Ha-to break the chains of tradition. Ri-to transcend the tradition. But again, it is a natural process. If one has not yet absorbed the full tradition of the Ryu, how can that one decide what is the right or wrong way of doing things? That is why the tradition of a Ryu is set forth, to allow those who follow it to learn from the successful experience of its founder, become one with it, and transcend it. It is so we aren't all just floating around in the void, but have something tangible to hold on to in our path. Shuhari: eat your heart out, Bruce!
One more thing to remember: any given Ryu was set forth as a result of a single person's own experience and interpretation of the art. Ryu were not divinely inspired. They resulted from a teacher spreading his personal method of karate to a group of students, who in turn spread it further. The founder's of the various Ryu understood Hacho and Shuhari, and wanted their students in the generations to come to preserve, as well as further their art. It is a fine line to walk, but provides us with a lilfelone journey to enjoy.