I posted this on another board, but wanted to bring it over here as well.
As a fan of Whedon's work, this idea that Whedon focuses on female characters at the expense of male characters strikes me as extremely ill-informed and smacks of intense generalization made by people who are already predisposed to dislike his work on sight (something that I also don't understand).
This really has nothing to do with the topic at hand, but let's analyze Whedon's existing work from an objective perspective:
Buffy the Vampire Slayer - Focused on a female protagonist; however, over the course of its 7 seasons, the series ended up being equal in terms of featuring both male and female main characters (6 on both sides). The character of Buffy herself did tend to overshadow many of the other main characters at times, but that is entirely appropriate given that the series was SUPPOSED to be focused on her.
ANGEL - Focused on a male protagonist; however, unlike Buffy, the 'gender balance' was more uneven and more skewed to the male side, featuring 7 male main characters over the course of 5 seasons and only 3 female main characters (Cordelia, Fred, and Harmony).
Firefly - Was much more of an ensemble piece than either Buffy or ANGEL; however, when it did focus its narrative through individual characters, it was primarily focused on Mal and River, and much of the story we got was told/filtered through their POV.
I didn't see enough of Dollhouse to analyze it, but, of the 3 series I mentioned, none were particularly focused exclusively on female characters other than Buffy, and that is because, as noted, the series was supposed to be about her, and therefore needed to focus on her more than other characters at certain points (although the argument could be made that the two most developed characters from the series were actually Willow and Spike).
Bringing this back to the topic at hand, I think the above analyses should demonstrate, to anyone who can look at things objectively, that the film is in no danger of becoming 'female-centric' even if/when more female characters are added to its cast.