Thank you both, Johan, as well as Noboru again.
Via Noboru's quote of and link to Murata-sensei's text, we had been reminded to distinguish between the meaning, as well as the outer forms of rei between schools of Kobudō and Gendai Budō. As this forum is named "E-Judo", I think we can turn our attention to the more modern forms of budō, and their use of respective concepts. And while people here, like DougNZ and myself, but also like NBK, as his "second art" (if I may say so), practise arts, that also are called jūjutsu, those shouldn't be mistaken as that older styles of jūjutsu, Murata-sensei is talking about. I don't think, that anybody of us would regard that, what he performs, as a training just for "killing one’s opponent", as opposed to "mutual flourishing".
Again, jūdō-etiquette is mainly considered from the angle of Jita-kyōei in that paper. However, there's also one point, I want to mention in particular. It's the closing remark:
"Bowing is ‘a form of showing respect to others’. However, expressing this form is oneself. Therefore, to express this form properly, one is required to manage oneself.
The question is whether this inner self is steady or not. Isn’t it so, that the essence of the true bow that is required of judo (budo) apprentices, can be found in truth? No matter how uza saki, saza uki and outward form changes..."
In that sense also, perhaps a bit less directly, compared with other points, I believe that reigi, reihō & Cie can add to one's ability to master all kinds of situations, as it provides training in "managing oneself". "Steadiness of the inner self" also seems to me to be something, which can not be bad to develop and maintain, and for very practical reasons as well. Finally, the expression of "truth", that can also be found in the last paragraph, reminds me on "reality", and what could be more dangerous in a situation of emergency, than NOT to be realistic, NOT to see and consider things as they really are? I think, it's better to accept truth and reality, perhaps always, but especially under dangerous circumstances.
The "attitude of losers of matches at tournaments" is also something, that is brought up in that text. This time, I would include the behaviour of the winners of said matches, too. Correct reigi teach to NEITHER lapse into expressions of anger or disappointment, on and off the tatami, NOR to lapse into some kind of silly jigs.
Therefore, reigi teaches to control one's emotions, an ability, which is another very practical thing, to my mind.
Regarding one citation of Kanō-shihan within the paper, I now myself deviate briefly from the actual topic of this thread. Murata-sensei writes:
"Kano says, ‘In each case, one is required to perform the bow from the heart’ and he warns against performing a bow superficially and only in form without involving the heart."
I often wonder, how anybody can think to have delivered rei, when the situation demanded it, while the only thing I could observe, was rather a queer form of headbutt.
Johan addressed "a bunch of rules in a crowded dōjō", and it's correct that they also have to do with safety, especially when weapons are concerned. However, this meaning today obviously is limited to the smaller world of the dōjō. I was thinking more along the lines of "real life", when I started this thread.
And, indeed, Johan also catered to that topic. He mentioned "physical posture", something, which I thought to have been included already in the link Noboru provided with his first posting. But then, Johan writes: "Another practical something is you can use your peripheral vision while bowing". He connected that with an awareness of maai. A very good point, I think! Now, imagine yourself even trying to follow the Japanese way, doing a bow a bit deeper and holding it an idea longer, when you are bowing to a higher ranked person. To practice correct reihō, in that sense, can also teach you to use your peripheral vision, AND react according to the impressions you get from it.
I think, we've arrived at a point now, that makes it easier to understand, what I meant with "the practical side of rei, reishiki, reigi, reihō, sahō, etc.". Could we still find some more examples for that?