I've been trying to get through "The Psychology of Clothes" (1940) by John Carl Flugel, it's just difficult at times to stay awake whilst reading it!
I ran across this passage, from page 175, which I found kind of interesting:
I've bolded the opportune sentence. I think when we see skirts being designed to go over pants, it's sort of harkening back to this mode or behavior he describes.John Carl Flugel wrote:This last fact, that the waistcoat had a collar and that this collar has a vestigial feature showing that the collar could be turned up, serves to remind us that the waistcoat itself is the relic of an outer garment, the upper part of which could be raised so as to protect the back of the neck. What was originally an outer garment has, in this case, become an inner garment; and this, in turn, illustrates an interesting feature to which historians of dress have drawn attention, namely, that when a new garment is adopted, there is a tendency for it to be put on over the old garment. This tendency has probably played an important part in the development of dress. Just as particular features of dress are slow to dis-appear, so also are individual garments themselves, which may persist even under circumstances that one would expect to lead to their disappearance. Sometimes, as here, an older garment is not displaced, but merely covered a process analogous to that which psychoanalysis has shown to take place in the course of mental development). The significance of this tendency for the history of clothing as a whole lies largely in the fact that it leads to an increase in the number of layers, one above the other, of which a costume may consist.*
*Though of course it is very far from being true that all inner garments or underclothes were originally outer garments.
Is his theory bunk? Does it apply to skirt-over-pants? From time to time we get into heated debate over which skirt (design, material) would usher in acceptance and wear by men - I wonder if this theory has any role in informing that discussion. And I don't think skirt over pants has to be the answer - perhaps the (sometimes reviled here) skort is the ideal transitional garment. With the shorts portion reassuring anxious men that it's just another form of shorts, with a decorative flap (or whatever construction - could be a full skirt - so long as it retains a pair of shorts).
)
I'll admit I don't like the skirt-over-pants options personally, but I've been finding myself wearing my ClHu utility skirt lately which is a rather utilitarian nylon skirt with sown in heavy sweatpants that are shorts length, they just peek out a bit. They're nice when the weathers cool but not cold and I'm doing stuff outside. I don't find jeans comfortable and I don't like just wearing sweatpants (there's a reason women talk about "grey sweatpants season" 
) and these were a nice compromise. A bit expensive for what they are but I got them on a good discount last year. It wouldn't be difficult to recreate independently.