For most women, once they have 2+ kids, it becomes non viable financially to return to work. By the time you've paid for nursery fees, you're often working for nothing. And feeling massively stressed out, having to juggle work and home life, for no financial gain.
It's the woman who has mat leave, taking out up to a year every time. Often makes sense for the man to have the unbroken career and climb the ladder, so he can provide for his family.
This is all well and good when a marriage lasts, and all income is treated as family money. I think it falls on its arse if the guy is a douche about money (claiming he is the earner and therefore the boss) or when a couple divorce and the woman finds herself on a very sticky wicket indeed.
Of course women can "have both". But show me one full time working mother who isn't stressed to the max. Yes, she's still a mother, but she has so much on her plate that it's (often) not enjoyable. And then there's the guilt of missing out on school plays/sports day etc, when other non working Mum's are there.
I have no idea what the answer is though.