Well, it makes them feel good, it makes them feel like they are a part of something greater than themselves, and it also makes them feel connected to the mystical, exotic and more interesting culture and life then what they live in already. These and other reasons drive practitioners into the use of Japanese terms, characters and ideograms.
What those terms actually do for us when properly translated and defined is provides us with a bit more insight as to the what, when, where, how and why of these interesting teachings from their culture and beliefs on martial arts. Granted, most terms are not translated correctly but with the advent of translations sites from the vasti-ness of the Internet Verse or Cortex, for you firefly friends, that ability to correctly translate simple terms increased ten-fold.
Terms are limited in use yet one of the benefits is that when translated we often find, as a direct opposite to English terms and words, the term, character and ideogram have “Several different” translations and meanings.
Example: Isshin [一心]
The characters/ideograms mean "one mind; wholeheartedness; one's whole heart." The first character means, "one," the second character means, "heart; mind; spirit."
Note: I remember that most never truly understood who, why and how the term, “Wholeheartedly,” became a part of the system practiced until someone pointed out the various definitions from the use of Japanese characters/ideograms, etc.
When you look at the group of defined English translations you will see, and as it is taught in the actual dojo that uses this term, that it deals with “Heart and Mind and Spirit” where further definitions and meanings can and do come from how practitioners interpret, perceive and gain perspective on from the study of the system and the martial discipline.
Yet, using them in the dojo, verbally, such as counting repetitions, etc. is more an ego self-soothing pride boosting and associative need from survival instinctual meaning not often conscious to the individual type thing.
I remember once a very prominent Koryu Practitioner said, “When I left Japan my Sensei told me that I should teach in America as I would for Americans, the teachings in Japan are for Japanese (and of course visiting guest students like this practitioner).” Now, I don’t have that quote exact but the meaning in his post/article was that one should use the cultural etiquettes of the Dojo and Sensei and Country/Culture/Beliefs where you train but when you go to another then train, practice and apply your knowledge and experience to that Dojo, Sensei (if not you), Country, Cultural belief system and that means using here English, American style clothing to train in, and so on.
Be aware that many also pick and choose, cherry-pick, what they want that relates to their needs and perceptions so that they benefit personally and directly rather than actually mimic that cultural belief system complete “Way,” to practice, train and apply said martial disciplines. We non-Asian martial artists don’t seem to be able to let that go, it has become ingrained and encoded as “What martial arts are,” when in fact it is about, “What we WANT martial arts to be!”
Here is the rub, in general, even those who want to totally and completely absorb the martial arts along with its cultural belief system heritages by traveling to the country of origin to train and learn are in for a huge disappointment. Those venues and avenues have succumbed to world commercialism to the nth degree. Almost all of it now caters to what we, the American or Non-Asian customers, want and need at the “Low, low price of …”
Then there is the conception of learning from the proverbial, “First Generation Students” of the masters from which they learned their martial arts but in reality, as to my experiences and research only, they were not exposed to those cultural beliefs as they pertain to marital arts and they were actually exposed to the more watered-down educational sport oriented forms of martial arts.
Except for the very few who truly were exposed, over long periods of time that span decades “In-country” practicing what we understand as “Koryu,” to traditional martial disciplines practically none of the modern martial artists were ever exposed to and trained in that more traditional martial disciplines.
One solid and positive aspect to all this is there are a few, and growing in numbers, who actually are taking the time and effort to seek out the traditional aspects and incorporate that, at least academically, into thier training and teachings. It is a bit like the martial arts self-defense world that lacks reality there is a concerted effort of the few experienced professionals to teach us “Reality-based adrenal stress conditions training” to get us closer to “Reality,” and the “Reality of Conflict and Violence.”