Patterns are a means to an end rather than an end in themselves. Hironori Otsuka's (founder of wado-ryu) book, Wado-Ryu Karate, stated that, "Martial arts progress from kata to kumite, kumite to combat, and so on. Kata is a fundamental aspect of martial arts and hence is unyieldingly important." Patterns techniques should be an integral part of sparring and self-defense training. By eliminating pattern techniques, such as throws, chokes, locks, etc. from sparring, we do not develop the skills and attitudes needed to execute the techniques in self-defense situations.
Not only do the patterns provide techniques, they also include the principles upon which the techniques were developed. It is important to understand why techniques work and their underlying principles, we must get beyond the mere memorization of movements. Principles are far more important than techniques. Principles may be applied in many ways, while techniques are very specific and limited. By concentrating on the principles and the various ways in which they may be applied, a single pattern may become an inexhaustible repository of martial knowledge. Understand the principles and you will be able to adapt any technique to be of use in any situation. In his eighteenth principle of karate, Gichin Funakoshi write, "no two fights will ever be the same, but the principles upon which the kata rests never vary." Choki Motobu (one of Okinawa's most feared fighters) once said, "One must learn how to apply the principles of the kata and how to bend with the winds of adversity."
If you only practice patterns for rank advancement or to compete, you are missing the wealth of knowledge they may provide. Through the practice of patterns, we learn from past masters and perhaps gain a little of their understanding of the martial arts.