The miniskirts were added to attract male viewers, plain and simple. In the end, this was a commercial TV show trying to attract the widest audience possible in order to make money.
Women themselves saw themselves in mostly traditionally female roles. Roddenberry noted in an interview (I have it on tape) that it was women who objected to a woman being the 2nd in command on the ship. Their reaction was "Who does she think she is?". It wasn't a case of women being kept down by men. Many women felt very comfortable in the roles that society assigned to them. Some didn't (hence the women's lib movement). It was only in the last half of the 20th century that women were duped into believing that they needed to be like men, develop a career on their own and shun any kind of femininity. Today, in most households where both the man and the woman work, women are still doing nearly all the housework. Instead of being in charge of the home and the children, women are now shackled with being a breadwinner too. I think they have been sold a bill of goods. They have been told that they must go out and conquer the world in order to be fulfilled, even though millions of women describe how being a stay at home mother and homemaker can be one of the most fulfilling experiences any human can have. Feminism today tells women that they are wasting their lives and living unfulfilled lives if they don't have a career outside of the home. They tell them they are losers if they stay at home. The feminist assert that women are being oppressed by men, but I submit that it is the feminists who are oppressors by making it socially unacceptable for women to follow a path other than pursuing a career outside of the home.
It is interesting that feminists are opposed to anything feminine. I think most people agree that it is women that have all the sex appeal. Men just aren't attractive. For example, if you picture a man wearing nothing but a pair of socks, this would either make you laugh, or disgust you, or both. A woman wearing only a pair of socks would be erotic. It is just the way it is. Women use their sexuality to get what they want. It has been this way since the beginning, and it will be this way until the end. Whether it is right or wrong, it is the way it is. Female singers use their sexuality to sell their music. In spite of a few notable exceptions, male singers generally have to rely on musical talent to sell their music. They may sell some music because of their looks, but they have to have some talent to back it up. That is not always true of a hot, sexy woman. An attractive male may appeal to half of the population, but an attractive female appeals to everyone. (Riker made a comment about how humans' last prejudice was for beauty in a NG episode.)
It is a mistake to think that women are not taken seriously if they are feminine or sexy. Actually, they are taken less seriously when they butch it up. I work with some very beautiful, very sexy women. Some of them I respect, some of them I don't respect. Some of them are competent, some are not. But I am sexually attracted to them all. What I am trying to say is that my opinion of them and my respect for them is based on their work performance, not on their appearance. Now, having said that, women's sexuality gives them a huge advantage in the workplace. If they are particularly sexy, they will use their allure to control male (and sometimes female) co-workers. This is not fair, but it is true. I suspect that this will not change in the 23rd or even the 24th century, if we make it that far. Was it right for the female crewmember to be ogled? No, but a good looking women is always going to be ogled. It doesn't mean she is incompetant, or incapable. It just means she sexually attracts men. The Trek women originally wore pants instead of the miniskirts. This would make the work environment much less sexually charged than a minidress. It seems to me, that if Trek were a depiction of reality, the women would not be wearing minis because it would be too distracting to the male crewmen, but even if they were wearing pants, their sexuality would still come through.
As far as the remark about how a crewwoman would get married and leave the service, this is a reflection of the expectations of the 60s. Women were really only in the workplace until they got married. After that, they would leave the work force and stay at home once they started having babies. In 2009 it is a real anachronism, but Trek wasn't make in 2009.
Was Trek against women? Obviously not. But it did acknowledge that women were sexual beings and celebrated it. Feminists today want to deny this, but it is the truth.
One way to sum up the relationship between men and women, not just in the Trek world, but in the real world is the following phrase:
"Men want it, women have it."