Due to the length of the UM article "Moden im Offizierkorps" ["Fashions in the officer corps"] (it is almost twice as long as the excerpt posted above), forgive me if I don't provide a full translation.
The article is about a talk delivered on the occasion of the February 1937 meeting of the Gesellschaft für Heereskunde. The speaker was the retired Oberstleutnant R. Wagner and his subject was a look back on the development of miitary fashions in the officer corps over the past decades.
One of his points was that non-regulation practices - unauthorized changes to standard uniform items or the wearing of completely unauthorized ones - are usually caused by inadequacies of the regulation items and the simple wish to make them more practical. He observed that many more such individualistic practices had taken place in the pre-WW I era, while in the present (i.e. 1937) officers and men mostly followed the rules, drawing the conclusion that the present-day uniforms were more practical than those of yore.
On the other hand, he noticed that the dreariness of modern field uniforms gave rise to a strong wish for more decorative elements; a tendency that could be observed in all armies.
Also, military fashion had always been influenced by civilian men's fashion to a certain degree.
The bulk of the speech/the article deals with examples of historic non-regulation practices of the pre-WW1 era.
I'll just single out three of the speaker's observations that I found to be particularly relevant here:
Up until the 1890s, soft, high boots with button-up closure were to be worn. Then, all of a sudden, they became unpopular and the lower, stiffened boot made its appeareance. "It was not fought, even though it was contrary to regulations; even the Kaiser wore it. The stiff boot became established. It may feel free to stay, as it became correct."
This is a fine example for the silent, gradual, no-fuss adoption of non-standard items that eventually get authorized to bring regulations in line with what had already become an accepted practice.
The Litewka was a very practical and comfortable item - especially in warm weather - but saw only very limited use, as its wear was restricted to within the barracks or while out riding etc. "Now, how could one go out to ride without the Litewka and then go riding with the Litewka? Thus, many questions arose, which could have been prevented by more liberal regulations, so as to assure a more widespread use for the practical Litewka."
A good example for absurd regulations whose very unpracticality provoked their being ignored.
"In order to champion the cause of the cap with a low top, all officers attending one pre-war race wore low caps instead of high ones. Detailed personnel from provincial regions believed that the low-top cap was the proper one."
If everyone does it, it has to be right...
From the closing sentiments of the article's author:
"Our readers know how much the 'UM' has stood up for absolutely regulation clothing. In order to maintain an ongoing adherence to regulations, it will be necessary in the future to have practicality dictate all uniform regulations. And, fortunately, nowadays this is the prime principle for all those who issue uniform regulations. It is just as self-evident that the uniform regulations have to acommodate fashion trends to a certain degree and that they have to attempt to increase practicality where it is possible."
A case is made to constantly re-evaluate and adapt the regulations so as to bring them in line with the real world, rather than stick to obsolete or simply wrong concepts out of a matter of principle; an issue which the speaker also addressed.