http://www.nber.org/papers/w19829
I agree that females who would have become nurses and secretaries in the past are now becoming physicians and executives, and without doubt this a good thing. My observation is just that by solving one problem (limited opportunities for women to become professionals) we inadvertently encouraged another (assortive mating on the rise which reinforces inequality).
It's also interesting you mention social pressure at different times in history. I am working my way through Downtown Abbey at the moment and it reminds me that throughout history there have been strong pressures for people to marry within their own class/caste systems. Probably for many reasons, but one of them is certainly the maintenance of wealth and power, which has typically been far less equal throughout those historical periods than the US is today. The post WW1 period in the US has been the exception not the norm.
If the nurse or secretary of 20 or more years ago was "from a good family", what change was really spurred by the union?
Additionally, I think you are conflating education with social standing, when they are somewhat different, and there have been different levels of social pressure against doing either at different times in history.