I am intrigued as to why some historical dissertation should guide us or provide any justification for our modern-day clothing preferences. If Mr Oettle prefers going about sans underwear that is his decision entirely but quite why he should seek to justify that choice on some historical foundation is beyond me. I can only surmise that he needs such justification to lend legitimacy to an activity that he would otherwise feel uncomfortable or even guilty about. I am not sure that many of us would feel the need to go about sporting codpieces or wear tights and powdered wigs but, by the same token, it is there in the history books so could be quite legitimately justified on a similar basis.
As to military traditions I have little knowledge beyond their purpose of reinforcing a common purpose, an esprit de corps, for the obvious reason of ensuring that a body of troops operate as a single force and without question to be at their most effective. Whether a similar imperative should apply in civilian life is another matter altogether.