Its an interesting one. I can see a lot of logic to the OP comments, even if he isn't correct per se. Rather, I think that it is something that Machida could have capitalized on, bu hasn't really done so.
As already mentioned, he does have a history with one of Japan's biggest ever stars ( Inoki ), has fought in Japan, is a master of one Japanese art and a former practitioner of at least two more. Of course, most importantly, his father is Japanese.
Added to the facts he is one of the most skilled MMA fighters alive right now, is the leading proponent of karate in MMA, has been a champion, has one of the highest levels of technique in striking out of anyone in the world and behaves with respect and dignity, then that leads to what could be considered to be a very potently marketable figure in Japan.
Perhaps if Machida had been more vocal about his Japanese heritage, and displayed more of it, and about it, in public alongside his Brazilian roots, then he could've maybe strengthened his own position in terms of drawing power, to the UFC.
If he had played things slightly differently, whether by natural means, or design, then it is more than possible that he could've captivated the Japanese market and made himself a big star over there, far more than you would guess that he currently is.
Very useful position to be in, if you are a huge draw in what is very big market in Japan, to go alongside the fact that you are already a star in Brazil.
Supporting - Machida, Edgar, Mitrione, Pickett, Cruickshank, Wiman, Lauzon, Falcao, Belcher, Korean Zombie, Palhares, Hendricks
Retirees - Lytle, BJ Penn, Hackney,