Without looking into any other sources of information, I'd say it's because the majority that play games have been doing so since they were young in a time when games were mainly marketed towards the male gender.
When you grow up with games in your life, it's not very hard to make the transition from basic controls to more complex ones, and so you continue gaming. Most women that I know did not grow up in an environment where they had access to games, and unfortunately we still live in a society where gaming culture and women still do not meld very well. With the only socially acceptable form of gaming to most women being the games found in an iTunes App Store, you can't really blame the majority of women that choose to stick with what they and their peers are comfortable with playing instead of venturing out to other gaming platforms. The exact same thing can be said about men too, however, as there are most definitely men that do not play mainstream games and choose to stick to casual phone gaming platforms as well.
Again, I'm not making a very educated answer as this is just me going from what I've observed, but as a female gamer who has grown up in environments where I was the only girl that played games, this is just the only reasonable conclusion I can come up with.
When you grow up with games in your life, it's not very hard to make the transition from basic controls to more complex ones, and so you continue gaming. Most women that I know did not grow up in an environment where they had access to games, and unfortunately we still live in a society where gaming culture and women still do not meld very well. With the only socially acceptable form of gaming to most women being the games found in an iTunes App Store, you can't really blame the majority of women that choose to stick with what they and their peers are comfortable with playing instead of venturing out to other gaming platforms. The exact same thing can be said about men too, however, as there are most definitely men that do not play mainstream games and choose to stick to casual phone gaming platforms as well.
Again, I'm not making a very educated answer as this is just me going from what I've observed, but as a female gamer who has grown up in environments where I was the only girl that played games, this is just the only reasonable conclusion I can come up with.