Mybe it's just because I mostly only read licensed manga, and most of what comes out here ends up dominated by the male, shounen or shoujo.

The men in Claymore get to be more useful that most girls do in shounen.

The thing of it is that it seems that it's subconsciously considered more "natural" for a narrative to focus, so in general, people notice more when it isn't focused on a male than when it isn't focused on a female, and the male-to-female shift is noticed and picked apart, but the female-to-male shift is the norm.