Marriage is indeed a sexist institution operating for the benefit of males that must be rejected by the heterosexual women who have the opportunity to do so.
Traditional Subordination
The central feature of the historical significance of marriage has been the sharp disparity in power relations between spouses. The woman has historically been a practical commodity in the man's life plan and her interests have consistently been subordinated to those of her husband. Yet one of the central arguments in support of marriage is this very notion of the historical significance of marriage in society.
Our wedding ceremonies today reflect the omnipresence of sexist traditions. Veils worn by brides are a central feature of the bridal gown and are often removed only once the bride is legally bound to a male (her husband) or once the father hands her over to her new male guardian.
The presence of the father is another significant holdover in wedding ceremonies. The father is still said to "give away" his daughter and often stands between the bride and groom for a significant portion of the ceremony until he verbally expresses his desire to give his daughter to her husband as though she were a commodity to be given.
Note also the practice of changing the last name of the wife to that of her new husband's. Her identity is dissolved into his just as her dowry became his in the Middle Ages. There are tens of other examples of the pervasiveness of sexism in wedding ceremonies and marriage, illustrating the lasting impact of tradition upon present day marriages.
Why Marry?
The next question to be asked is why women would choose to marry. The most popular answer is probably that the individuals love each other and want to spend the rest of their lives with each other. Couples often feel that marriage is the only way to express this high level of commitment to each other.
But this is hardly true. If two people want to live together or stay with each other for the rest of their lives, there certainly is no need to have legal permission to do so. The couple may simply make that decision between themselves. And the desire to express commitment to one another in a public setting can be done through countless ways other than an official wedding ceremony. Marriage is simply the traditional way to do so.