I usually keep quiet in these forums, however this is actually a fairly important issue, so I will weigh in...
As Dave pointed out earlier, there is an accepted terminalogy in all specialties, whether it is the Latin in scientific nomenclature or English terms in physics, which are unintelligible to the rest of us. To borrow from some other arts which use phrases like "horse stance" or "child's pose" or "Dragon claw" it doesn't matter whether or not it is English, they are still specific terms used in that specialty. It simply remains that with Aikido's roots in Japan our specialized terminology is Japanese. It doesn't matter that the phrases are not used in everyday language, we don't use "horse stance" in everyday conversation either.
As Anna pointed out, to throw away the many Japanese links, be it the etiquette, the bowing or the hakama, etc, we would be throwing out the roots of the discipline. And Aikido with it's traditional roots has kept that discipline much more so than most martial arts in the western world. The discipline is important and makes us better individuals.
Of course Daniel is also correct that we need to define these concepts to beginning students, this is important. As was discussed previously in this Forum, Aikido continues to evolve and our explanations of these concepts continues to evolve as well. Our explanations to our students may sound nothing like the explanations our Senseis made to us.
I find that beginning students need time to learn the terminology and when calling for a given technique on a students's first test I call for it first in Japanese (as in "katatekosatori kotegaeshi")and then say the attack in English (as in "cross-hand grab kotegaeshi"). There is no substitute for the name of the technique (kotegaeshi), that is it's name, and nothing else will do.
It takes different students varied lengths of time to know and understand the terminology, but by their second test most students are quite comfortable with the terminology. Of course, we have all seen tests, even with advanced students who stare at you as if they've never heard those words before in their life! And in those cases it would make no difference what language we are speaking.
However, as Daniel points out "kotegaeshi" means nothing to a beginner, no matter what the language. So our task as instructors is to explain and show. Written descriptions would be very nice, and Daniel, if you use them in your dojo, I would love to see them as they are perhaps applicable to us all.