The thing is, many minifigures are (or at least, were) genderless or could easily be interpreted as female. Anything without preprinted hair could be used for a female minifigure, it just requires a female hair piece (and for equality!!!!! males often required male hair pieces).

Circled in blue indicated gender neutrality. Some are a stretch, but my sister (and every girl I've ever met who has talked about related things) do not play with sci-fi soldiers blasting red and blue space mutants, or mining underwater crystals with giant crab monsters, and I think us boys can keep our ice planet destructo insect aliens (which still have female minifigs in them).
That said, a lot of the current non-licensed sets come with at least one female. City sets have a lot of females. Star Wars, believe it or not, has a lot of females. Even the
dinosaur fighting sets included a female.
Another thing is that sets are not generally catered to "being built and put on a shelf" (aside from a few exceptions, eg millennium falcon, death star 2), and are more catered towards the "taken apart and made into something original". My sister had managed to outweigh her female-to-male minifig ratio with ~4 female hair pieces I gave her to change her indiana jones into laura croft clone #74.
Lego is not the place you want to be if you're defending feminism. It is a construction toy, and if you stop making the pre-assembled sets and make something creative it wouldn't be an issue.