I agree with your first paragraph. I think we have some built-in mechanisms to evaluate each other socially, and probably in the Stone Age a woman couldn't just fuck anyone, or she'd be a burden on the tribe. But now that we have condoms, birth control, etc., I don't see why they can't sleep around. I personally don't see anything wrong with promiscuity if the person is intelligent in how they go about it.
It makes sense that men have less control now that women have the right to vote, equal wages, and so on. They're also more represented in academia at this point. My opinion on women and politics would be a completely divergent topic. I think emotional bias is a weakness when you're facing people who mean to crush you into dust, but they smile in your face. But equal wages, equal workplace opportunity—Good things.
Overall, I don't think industrialization or how civic rights have changed makes much of a difference in how sexes behave. I think that happens at a genetic level, and beta males will still enjoy less sexual activity. And attractive women will still have their choice of the pick of males. This is how it's been, and it's how we are designed to be for the sake of producing successful offspring. Men won't be phased out, because by instinct the female seeks the masculine.