formula's that deliver money in the end that are hard to move away from for Exec's. New paradigms are hit and miss so Exec's play it safe so the money can come in and unfortunately in general testosterone based games sell.
It's like the 2D to 3D phenomenon, a lot of companies still made 2D games even though 3D was available. A shinning example of that (and also trying to assure themselves success in a new paradigm) was the one of the first 3d games that took advantage of 3D cards, Tomb Raider. I don't think I have to go into the whole Lara Croft issue but it is also an example of why 2D and 3D brain games have had success. I see it filling in a missing niche in the market place that could be primarily made up of the female gender, that would be fascinating research.
Honestly I don't see why making a female model and adding all the animations that the male models have to it, is that difficult. Someone has to spend time on it but for all the time and energy during the development stage that's wasted on do over's or new design directions, it's not that much.
my 2 cents.
-p