Let's be honest here, more men play video games than women, especially when it comes to the more 'hardcore' style games. A lot more men. Thus developers tend to cater to their intended audience.
When more women get into gaming as a hobby and make themselves known as an influence within the medium things will change, until then you'll have the majority of hardcore games catering towards the majority of their audience. It's a pity really, but there you go. Sort of a self-perpetuating circle: not enough women play these sorts of games and so developers generally don't try to appeal towards them which, in turn, discourages more women from playing games.
Statistically around 2 in 5 'gamers' are women which sounds encouraging until you realize that of those around 80% primarily play on the wii, where it would be a fair guess to say they're not playing games like Resident Evil 4
(Which was awesome on the wii) but more of the wii sports, wii fitness type of games.
source
Again it's a shame but there you go.
On a side note I continue to disagree with you about The Witcher, but I remember we've talked about that before in a previous topic and I really don't feel like another bout of pointless debate that will change nothing.