I can't really reply for the radical feminists you spoke to, but there's a chance that they might have tried to communicate the kind of idea I shared above:
See, some feminists feel that distinguishing between "sex" (the biological dimension) and "gender" (the socio-cultural construct) is already going too far; to them, it's basically the equivalent of saying there's valid racism (intelligent Jews, athletic Africans) and invalid racism (KKK). The moment you construct the kind of fundamental chasm between people, stereotyping them on account of some physical characteristics, you've already crossed the line.
I'm not sure whether I agree completely with them, but I see where they are coming from. If you told an African that it's his natural role in life to be an athlete rather than an academic, that'd be pretty offensive - but tell a woman that her "natural role" is to stay home and raise the kids, and all of a sudden it's socially acceptable.
First, IMO, your use of race to compare to men and women is flawed. Because there are Black men and Black women. Each falls into your role argument with regards to sexism. The male-female relationship is unlike any other human interaction. Especially in the Christian worldview (reminder you came to CF to discuss this). Unlike is low balling it to say the least. The TaNaKh (OT) and Brit HaHadashah (NT) teach us that men and women cannot be without each other. There is a natural longing for each other and it's not just sexual (as the post-modern Dawkins world would have us believe).
So here's the Biblical view of the relationship between women and men:
In Genesis we have this:
"So God created man in his own image, in the image of God created he him; male and female created he them."(Genesis chapter 1)
So both men and women are created in the image of God. So see no sexism there.
Now what did Jesus Christ say based on this?
Matthew 19:
4 And he answered and said unto them, Have ye not read, that he which made them at the beginning made them male and female,
5 And said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they twain shall be one flesh?
6 Wherefore they are no more twain, but one flesh. What therefore God hath joined together, let not man put asunder.(KJV)
So Jesus tells us when a man and woman join they become one flesh. Wow, what a radical Jesus was! That does not sound sexist to me at all. One flesh.
Now I know you focused on roles. Do you have an issue with a Christian couple who are 'one flesh' in the eyes of God to have the husband work the fields, or any job while the wife raises the children? Does the woman have to work outside the house and drop off her kids with strangers to raise to meet your idea of busting up ancient sexist traditions?
Finally, as logical beings we can look at history, most of it modern to see what works best. Is our society any better now than 30 years ago with regards to raising kids, kids passing in school, and becoming productive players in society since most men and women decided dual income and day care works best for that McMansion and his/her Beamer in the driveway?