lightbrite- it’s not about today’s standards. The Halacha always was that a married lady’s hair must be covered, knees must be covered and sleeves must be uptil or covering the elbows. This is how Jewish women dressed for thousands of years. Actually, throughout most of Jewish history, they were far more tznius than they are today.
It is only recently that the tznius standards have fallen. I am referring to 1940 as recent. In light of thousands of years of Jewish history, that is recent. Remember, the Bais Yaakov movement was started precisely because the Jewish girls were starting to go off the Derech. The Bais Yaakov movement, when it first started, was almost like a kiruv movement. The girls were not necessarily that strong religiously when they first came.