I realize the answer to my question is quite obvious, only it isn't. I mean, obviously, Japanese arts are Japanese, is why they use the Japanese language.
However, one thing I've noticed across this forum and others, is that only the Japanese artists seem to describe everything through the Japanese language. All of the other arts are usually translated to English. What's even more strange, is the arts which influenced Japanese arts (Kung Fu), and arts inspired by Japanese arts (Taekwondo and BJJ), do not do this with their native language.
We use a small amount of Korean in my TKD school, but 99% of the time we speak English when we're discussing techniques. Front kick, side kick, reverse punch, high block, sweep. All of these words are in English. Similarly, whenever I see someone discussing Kung Fu strategies on here, or I watch videos of BJJ techniques, the concepts and techniques are all spoken in English, instead of Chinese or Portugese.
And yet, more often than not, if someone comes into a conversation with their Karate or Judo background, they'll say something like "if your opponent has good kisame kicks, and has a fast right gyaku tsuki, you can use kiba dachi almost kokutsu dachi, and then gedan barai." They say this as if it's supposed to mean anything to someone taking Taekwondo.