To be quite honest, the only thing that appears skewed is your impression of what constitutes a game
![Smilie](/tfp/images/smilies/smile.gif)
WoW and similar games do mainly appeal to young men and as such they constitute it's largest audience. The Sims Online, on the other hand, is still an MMO yet is by quite a majority a female audience. Funnily enough, with the majority of females being, well, female, they tend to prefer games of a different genre. Expecting otherwise is silly.
(BTW, the ESA study was not just taken from polls but from data from nearly every main publisher in the US. As such, it wasn't a small poll of maybe 1000 people but information gathered over the year from basically every source available)