Dresses were still the norm, but gone were a lot of the frilly embellishments; part of the reason was rationing of materials, but another part was the impracticality of such showy garments when working in factories.
What they failed to realize was the impracticality of carrying around a stiff-brimmed hat along with the gas mask, helmet, and whatever other gear was actually necessary to the footsoldiers on the ground.