So, without further ado, let's look at the history of the skirts and trousers in question.
In ancient times, clothing was very simple: just one piece of cloth. Think of it as a large furoshiki (wrapping cloth). Men and women used to simply wrap this around their bodies. In other words, clothing started out as something rather like a skirt.
However, about 600 years ago in Europe, a fashion that looked like pants appeared. Compared to previous clothing, these were more convenient for riding horses, so they became popular among men.
This continued for a long time. During that time, the shapes of both skirts and pants changed considerably. However, since that time, the fashion of men wearing pants and women wearing skirts has taken root.
In the past, women did not wear pants. However, around 200 years ago, women gradually began to wear trousers as well. The reason for this may be that trousers were easier to move around in than skirts. Thus, women gradually began to wear pants as well.
Thus, in ancient times, men also wore skirt-like garments. However, after wearing only pants for so long, they must have forgotten all about the days when they wore skirts. Moreover, there was no need for them to wear skirts that were difficult to move around in now. This is the reason why men now wear only pants.
In Japan, both men and women used to wear kimonos. It was not until the Meiji Era (1868-1912) that men began to wear pants and skirts as they do today.