As noted before, it's less about women underestimating their own agency, and more about playing the game the way that it is currently constructed. I'm all for changing the game, but it's a bit of a catch 22 right now that women being too assertive is disliked by many men - which is why women tend to give off more subtle cues about interest rather than relying primarily on overt ones. As far as we've come there is still a huge undercurrent and backlash against strong, assertive women. We see it in politics, in work environments, and in dating. Until that changes, most women are going to continue to keep playing the game in a way that is less likely to get them negative backlash.