Lyoto Machida competing in a UFC title fight proves that karate is useful in MMA. So now there is another question: can other traditional martial arts be useful in MMA?
My answer is: "Sure, why not?"
What are the differences between traditional martial arts and MMA? Traditional martial arts have been about secrecy, empiricism and positivism. There are certain types of skills that they logically explain, but they're not open to the outside public. Why? In the ancient samurai era, people were fighting to kill one another; there's no way to teach those skills to people as "sport."
Of course, not every skill is a secret. Michihiro Omigawa and Hiromitsu Miura have told interviewers how throwing skills depend on experience, training a lot and learning how to feel where an opponent's balance is. So, sometimes, western training partners may think they're keeping secrets, but they're not. Some skills can't be taught in words.
Sengoku champion Satoru Kitaoka is known for his fast submissions, but he's had lessons from Japanese taekwondo pracititioner Kazuo Tachi. Tachi's gym is the home of Yoriko Okamoto, an Olympic bronze medalist at the 2000 Sydney Games.
Taekwondo separated from karate, and entered the Olympics as an official sport in 2000. It's had its own evolution as a sport. Sport taekwondo is like fencing, because when a fighter strikes with a legal attack, he gets a point. Therefore, taekwondo fighters prefer direct methods to reach opponents.
Yu Ueda is a fighter on the rise. He will face Kotetsu Boku, who is known as an elite fighter. I don't think he will win against Boku, but Ueda is definitely an interesting fighter, as he uses taikiken in MMA.
Taikiken was developed by Kenichi Sawai, who was taught by Chinese martial artist Wang Xiangzhai. Ueda hasn't said a lot about his style, but how he beat Jin Kazeta with his stance is easily recognizable and interesting.
"The complete fusion of attack and defense is the beauty of traditional martial arts," said Ueda.
This quote is enough to explain the beauty of traditional martial arts.
Big thanks to Jordan Breen (from Sherdog) for English advice for this post.
Big thanks to Chris Nelson (from Bloody Elbow) for English editing.