In terms of evangelical conservative views, of course they make terrible wives and mothers, ...
I admit that I only know 4 evangelical conservative Christian families (which is probably dwarfed by the extensive studies that you've done); however, the women in the family tend to be well educated.
Family A: Mom has a degree in nuclear engineering. She worked the field until she realized that the public school system was completely failing her kids. She home schooled them until they entered high school. Their daughter is now studying to be a vet.
Family B: Mom has a degree in mathematics. She decided to become a teacher before home schooling her children. The oldest daughter went to one of the military academies. The younger daughter received a full-ride plus massive stipend to attend the state university.
Family C: Mom has a computer science degree. The oldest daughter is now studying to become a medical doctor. Youngest daughter is still in high school.
Family D: I don't know what mom's degree is in. The daughter completed her pre-law degree and is now in advanced studies.
My family is far from being an evangelical conservative house hold. My wife has a computer science degree and her entire division was laid off as a result of 9/11. The kids liked having her home for a change and seemed much happier. My wife eventually went back to work full-time. The kids weren't as happy after that. Your mileage may vary.
Like I said, I only know four evangelical conservative families so it is only anecdotal data -- but then again, I didn't see you even attempt to quote a study beyond the "everyone knows" category.