Swords in a non-reenacting situation

[JSFMACLJR]

So we've established that at formal events they are no longer worn, but when/why did this go out of style? Did the natural "casualization" of our society do it, or are there other reasons why we went from this:


to this:

The Spy cartoon shows the then Marquis of Tullibardine wearing the uniform of his father's army, The Atholl Highlanders. That uniform is still worn.

Kind regards,
Sandford MacLean