Thanks for your reply. Your post prompted me to do a little web searching which ended up leading me to Jo B. Paoletti's books "Pink and Blue: Telling the Boys from the Girls in America" and "Sex and Unisex: Fashion, Feminism and the Sexual Revolution" which I have just finished reading. I found them both a very interesting read and very accessibly written. (For those interested in the TLDR option, I would suggest the chapter on the Peacock Revolution in Sex and Unisex.) Her research definitely supports what you said about the unisex clothing trend of the 60's and early 70's doing more to move women's clothing to incorporate some formerly masculine elements than vice versa.
I cannot speak for her but I also think that Paoletti would argue that this is not a conspiracy. One thing she suggests is that what ultimately emerged as unisex clothing represented the aggregate effect of many different people all trying to figure out what they wanted and pushing in different directions. The movement was very heterogeneous in composition.
A second phenomenon that she points out is that both the first wave of feminism (think turn of the last century suffragettes) and second wave (think 1970's women's movement) both saw conventionally feminine clothing as and norms in a negative light, as something holding women back. They were primarily focused on women obtaining access to things reserved for men (from the right to vote to careers, etc.). So, that social and intellectual context played a big role in tilting unisex clothing in the masculine direction. (Conversely, she also underscores the unfortunate role of pervasive homophobia pushing men away from adopting more conventionally feminine clothing styles.)
In Sex and Unisex, she argues that what any particular generation sees as traditional gender norms for clothing often goes back no further than their childhood. In Pink and Blue, she documents how what is considered masculine or feminine, or even whether gender differentiation should be the primary focus of children's clothing, varies dramatically over time. In Sex and Unisex, she argues that there has historically been a pendulum effect where those dressed one way as babies by their parents swing in the opposite direction when they dress their own babies.
At the very end of Sex and Unisex, Paoletti suggests that the gender binary that contrasts masculine with feminine may be running out of steam in terms of cultural influence or usefulness. One way to interpolate to the present thread might be this: Instead of thinking of skirts or other items of clothing as inherently expressing masculinity or feminity, instead, think of the specific attributes conventionally associated with feminity and think of wearing skirts as a way for men to express those specific attributes. For example, just off the top of the head, instead of thinking of wearing a skirt as expressing feminity, one could think of it as expressing empathy, kindness or supportiveness. In the process, the idea is that men wearing skirts begins to weaken the association of these traits with feminity.
My sense from reading Skirt Cafe is that one can distinguish two substantial contingents of men wearing skirts. Some make use of the conventional association of skirts with feminity to push back against the conventional association of feminity exclusively with women; Others make use of the conventional association of feminity with women (and masculinity with men) to push back against the association of skirts with feminity. So, the same skirt can mean something different when one man wears it from what it means when another man wears it. The general understanding of what a skirt signifies on a man will then reflect a dialogue between these different meanings. (And maybe some just find them comfortable or like the profile of an A-line skirt.)
Paoletti, J. B. (2012). Pink and Blue: Telling the Boys from the Girls in America. Indiana University Press.
https://iupress.org/9780253009852/pink-and-blue/
Paoletti, J. B. (2015). Sex and Unisex: Fashion, Feminism and the Sexual Revolution. Indiana University Press.
https://iupress.org/9780253015969/sex-and-unisex/
