Women's clothing doesn't have to follow a particular form as long as it is modest. That's not to say that Ihram as it applies to women presumes more freedom for them; rather, it's a reflection of the assumption that women, whether heading for the hajj or the corner market, are dressed more restrictively to begin with.
Ihram's symbolic clothing has two purposes. The first is to reflect a total equality among men, regardless of their backgrounds and station in life. Before God, Islam teaches, all are humble, all are equal, and worldly differences of race, age, nationality, class and culture do not apply.
Ihram's second purpose is a metaphor for how men will present themselves to God on the Day of Judgment. With that in mind, pilgrims often hold on to their ihram in order to be buried in it.