Jay hit on some good points:
Society has told us that men do the approaching. But with that old school view, women have to choose the best guy out of the group of men that had enough courage to talk to her (i.e. she is settling). Sometimes she may get lucky and a great guy will approach her and settling isn't so bad...but if women start approaching men, they can meet guys that they are attracted to as well. And the more people that a woman meets, the better chance one of those guys is a really awesome guy.
Which brings me to my next point (and Jaybot's point), women (straight ones) are looking for men of high value. This doesn't mean he has to own a porshe, a penthouse suite, and a 6 figure salary. It has nothing to do with money. Women want to meet guys that are fun, know how to turn them on, and know how interact with them. That is naturally left up to interpretation because not everyone is looking for the same type of person.
Female game is much different and yet somewhat the same as guy game. Male PU was originally (and still for the most part) designed for men to be able to have sex with more women. *Note* I'm not saying that this is the sole purpose of all guys...there are guys who want other things out of it and sex is not mutally exclusive with those other facets. But female game is not designed to allow women to have sex with more men. You're right, women can have sex much easier than men if they wanted to have sex with any random person (although that isn't true acroos the board--there are men that turn down women bc they are just some random person, they arent attractive enough etc...).
But along with that, not all women are knockouts. Not all women are 7s, 8s, 9s (oh god the rating scale!!

). So what are the 5s suppose to do? Sit back and be lonely? Lower their standards because they are not pretty enough to attract a high quality man that is also attractive? That isn't really fair and a double standard. But PU can be for all women whether you are a 1 or a "10." It is about how to interact with guys. Think of women that you dating that you dumped because she was crazy, possessive, just not interesting, just didn't push your buttons etc...
All-in-all I think the main focus of female PU is that most (though not all) are looking for relationships and not many guys and much sex. Lines and routines are not that big of a deal. You can throw a line in there now and then but high value guys respond to attention and interest. If you ignore a high value guy too long he will move on. Negging isn't really needed, though teasing and flirting are great. Kino is a must. And an understanding of how guys work and feel is a great bonus. When I talk about things from a male perspective they are amazed that I understand them to that degree.
And last and certainly not least, looks. Women must learn that guys judge looks a lot more than women (though wome still place a great amount on looks as well). For women who don't have model looks or even close to them, those women need to learn how to not be friend-zoned. After doing as much as they can for their appearance, they need to know the tricks to get guys thinking of them as more than just a friend (and thus another long post so I'll stop there). Feel free to message me if you have more questions because that is definately not everything to it.
A question I recently posed to some guru's out there was along similar lines. Why do so few women actually approach men? "Night Game" it is more common, but still not an every day thing. Day Game? Well, it rarely happens!
So bringing up the ambition to spread the word of women opening men....well I am going to give you 110% of my support. There really should be no reason we have to do all the grunt work