This is grossly simplifying the problem.
Women and men do not inherently prefer different types of activities (or any activity at all). There IS biological predispositions that can provide barriers (strength is the most obvious), but the desire to do certain things is, in fact, a social construct set in a sociological context. A sociological context is unique to a particular TIME in a culture (i.e. cultures are not static). Men and women in our culture tend to prefer different types of activities specifically because they are raised in different ways. This is specific to cultures. What is feminine/masculine may not be in a different culture. The Etoro tribe in New Guinea is particularly homosexual, and in fact considers the ingestion of male **** to be a necessary act for sexual maturity. I have a feeling you'd be hard pressed to convince young men in our society to start drinking ****. But in their society it's normal and accepted, so society functions. It's like this with any culture.
Should we despise a woman who decides that her family is more important than her career?
No, and no one is saying that. You do get some stupid ass feminists that get upset because they feel these people hurt their causes, but for the most part no one has any problem with people that choose that type of lifestyle. If our society had women okay with that type of role, and they all did that type of role, then there'd be no problem. The issue is that there is a problem with the role. And that's where the struggles and issues start to arise. There is systemic discrimination and it's so ingrained into our cultural psyche that it's so easy to overlook. Then you get people who say "well maybe women are just geared to be that type of individual." Of course, because it makes it easy and helps ensure the status quo.
Should we make fun of a girl who likes a frilly pink dress more than blue jeans? Frankly, having been a teacher, I can say that I've known schoolgirls with a house full of brothers and a tomboy mom who prefer dresses to pants. The societal pressures on girls to dress like "girls" is FAR less than the societal pressures on boys to act like "boys." A girl wearing jeans and a masculine shirt is not going to suffer playground torture. A boy coming to school with a dollie (that is a doll without a weapon of some sort in its hand) is almost certainly going to draw comment from other boys. Not the nice comments, either.
Of course. Now you see this as being a problem for boys though, right? Women are free to choose whatever, whereas little boys are not. The funny thing about this is that the main reason for this is our society's cultural heritage IS patriarchal, holding our standard male archetypes as ideals. Women are okay to act more like men, because the underlying desire to possess those traits is highly sought after. The idea that little boys would NOT want to embrace the idea of a man's man is SCARY to many people. It's seen as abnormal and people spend thousands of dollars investigating why their little boy would rather be feminine (this is where gender differs from sex) and do "girly" things. Male homosexuality is seen as more dysfunctional than female homosexuality.
But there's still lines. Women that are perceived as promiscuous do get ostracized. Young men getting into physical altercations are seen as "boys being boys" but women getting into fights are more likely to actually be incarcerated for it. In fact, if they are seen as sexually promiscuous (aka sexually deviant), historically they are even MORE likely to receive harsh penalties in the legal system. But I digress.
The systemic discrimination part of it is that many (I'd wager most) of the higher paying jobs have been dominated by men. You can, perhaps even rightly, state that it's because women have not been interested in these jobs. Taks briefly touches on this when discussing engineering, and it's true. Much of that is due to the gender roles that society placed on people. Women weren't expected to be professionals. However, this doesn't go back THAT far in history. In fact, prior to the industrial revolution, women were actually much more active in the marketplace. Women ended up getting most of the shaft with the industrial revolution, for really two reasons as far as I can tell. First, their jobs were often the ones replaced by machinery. This is unfortunately, and I don't really feel bad about it, in that I don't think it was a conspiracy to remove women from the work force. Not only were their jobs being replaced by the loom and whatnot, but the unfortunate situation that this equipment was in fact quite heavy did give men a leg up in using it. This is a form of "institutional discrimination" (nobody is meaning to be discriminatory, extra circumstances just make it so and there's not much that can be done about it aside from making equipment lighter...not an option back then). The unfortunate thing is that in many places, male dominated unions took up position in these occupations, and then restricted access for women.
According to Joyce Burnett (Gender, Work and Wages in Industrial Revolution Britain), gender ideology did play key roles in restricting access for women in job that did not require strength, but were not subject to a competitive market (the white collar jobs). Tailoring, however, utilized women to undercut men labour union wage demands and ensured a competitive market. In Burnett's perspective (one that minimizes the influence of gender ideology), competitive labour markets helped women maintain employment in said markets.
Another symptom of the era was that gender roles were being redefined. The ideal of the Victorian woman was a role that was seeing increased social status. This is where the cultural context is important. In this sense, with women seeking increased status by adopting the Victorian image for how a woman should behave. During this time, we saw women becoming less likely to enter the labor market because greater status could be obtained elsewhere. Not much of an issue for the time (a modern feminist would disagree, but she's looking at it in today's context), but it has led to "problems" for women in the job market the past century. It allowed men to become more entrenched in the labor market.
This is getting long, but I'll fast forward to today. Thanks in part to WW2 and the competitive labour market, more women are in the workforce. However, the white collar jobs still have limited penetration by women. Much of this is from gender role expectation (women shouldn't be doctors, they should be nurses). This is why that annoying feminist that we all hate spouts forth all of her rhetoric about how women can do whatever they want. The discrimination is two fold as well. You DO have people that think that women are, in fact, inferior doctors. It's all a part of the gender ideology that men are doctors. As much as people hate it, this is the ideal behind affirmative action. Because if you put people in a situation where they have to be treated by a female doctor and things go well, the stereotypes will start to break down. Furthermore, people will start to SEE people in these professions, hold them to new ideals, and you'll start to see an increase in enrollment in these fields (such as what taks mentioned).
But there are indeed still walls that are still up. It might not be a "global conspiracy" to keep down women, but there are people that resist the changes to the status quo (this is inevitable). Heck, I know in Canada the mere idea that a husband could rape his wife was laughed out of the House of Commons initially. It wasn't until I believe the 1980s that it actually got recognized that spousal rape can and does occur. The **** aspect of it for them is that, until recently, women were most likely to have to deal with the double shift. The "pink collar ghetto" meant that women were working in the workforce, and the primary workers at home. Fortunately this seems to be changing. But women don't just tend to gravitate to certain jobs. Societal expectations WILL make some jobs more appealing, because it's socially acceptable (nursing for instance has a huge barrier to MEN), but I just don't buy that through sheer coincidence, women tend to gravitate to lower level jobs that typically don't pay as well.
Cultures change, and with them their gender roles.