Speaking as a 3d-modeler I can tell you it's very very hard to make normal male OR female hairstyles in 3D... stylized hair-styles are much easier. Clean outlines and flow, very easy to "sculpt" .. and so these hair styles are all clearly sculpted, which is why they are all 1 solid block with no texturing aside from color/normal map. This is a very cost effective way to do hair (not meant negative, for a game like this, I can totally understand why they do it that way)
Realistically, if you wanted "real" hair on the characters, you'd need to spend SUBSTANTIAL amount of time actually modeling the hair flow (or at least model the hair strands, and let a physics plugin "settle" it), alpha mapping the ends, making sure they cast shadows and overlap nicely and all that. It is not easy, and would be really, really hard work, unless they have a specific hair modeler/texture artist.
