Abwehran, these guys would like to disagree with you.
As you see in the last picture, those guys seem pretty used to operating with machinery in dirty work environments.
In fact, when the work kilt came to our stores, i couldn't get one because it was constantly sold out. I have friends, both male and female that work in it during summer. it's sturdy, practical and lets your private regions breathe. Don't get me started on the impracticality of pants-induced fungus!
This particular skirt is made of canvas, but i have no doubt that the future will present us with more interesting sturdy fabrics.
Of course, there are certain jobs/work conditions that make skirts impossible, but those require all skin covered, more or less, for protection (Like welding. If you don't get burnt directly by occasional molten metal, then you'll still get one hell of a second degree burn suntan...) Those jobs often require very specific protective clothing that can't be solved with a singular uniform fit for all occasions.
So, i'm all for skirts! My only nitpick would be that the skirt has to be longer, so it covers the thighs entirely. They need the cover of fabric (even in skirt form).
(oh, and if you like the kilt, here's where you can buy it
http://www.blaklader.se/sv/produkt/85661370-kilt-hantverk )