Dresses are cool in hot weather
They accomodate a range of figures and body changes better.
If someone offered me a job interview tomorrow, I could go to the wardrobe and pull out a classic smart dress. I wouldn't have to fret that my thighs are an inch bigger in my work trousers, or that the cut of trousers in style has changed.
Trousers should be avaliable to women too as they also have their benefits.
Dresses and skirts aren't going anywhere because they are practical.garments for many.
The archaic garments OP mentioned were impractical.adornments to show otf status which is why they fell out of favour never to be seen again after their decade/ century in bloom.