you can't say "because there aren't any popular books with strong female leads being written". that's not true. there's the books about jacky faber, or betsy in the undead series, any one of robin mckinley's books, or the works of patricia mckillip, anne mccafrey, and of elizabeth moon. they're there if you bother to ask anyone who isn't a middle aged male director where they are.
i can count on my one hand the amount of big budget fantasy films which were made in the last several years which have a strong staring female role who can save themselves thank you very much; alice in wonderland, underworld, pan's labrynth, the work of hayao miyazaki, coraline, v for vendetta. okay. maybe two hands. but still.
the ones with a leading cast of mostly males? there's the lightning thief, the sorcerer's apprentice, harry potter, transformers, star trek, the lord of the rings, star wars, the current batman franchise, spiderman, eragon, how to train your dragon, iron man, where the wild things are.
one's which were thankfully balanced; avatar, crouching tiger hidden dragon, pirates of the caribbean, x-men franchise, narnia franchise.
i love to watch and read science fiction and fantasy. i'm a woman. can't i have any awesome fantasy movies with strong female leads on the silver screen i can relate to and feel empowered by? i shouldn't just be stuck in the history department (though all those real women are awesome, and when are they going to do a movie about catherine the great?).
oh, and i loved the new alice, wacky wardrobe and all. it was visually amazing, highly creative, and more true to the books then most portrayals.