I myself started a thread much like this one. Here's the link:
http://www.escapistmagazine.com/forums/read/9.187052-VG-women-you-actually-respect#5706902
I didn't go as in depth, but kudos for doing so.
Unfortunately, gaming trends are dictated by the masses, and the masses love their jiggle physics. Also note that the sexualization and overemphasis of both genders didn't really begin until games went 3D. The focus on "realism" in gaming has brought to the forefront the supposed fantasy of the everyman: to be a tough, grizzled, manly man with a Jessica Rabbit clone on your arm.
Opposite end of the spectrum in modern day gaming wouild probably be the Ratchet & Clank series. Beautiful and imaginative worlds, characters, and weapons with the right level of comedy. The love interests in those games are mostly directed toward the hero, not the person controlling him, and the hero himself is a short, fuzzy guy with a big wrench(yes I know he's a Lombax).
I guess the point I'm trying to make is that if we didn't focus on "realistic" games, or even games starring humans, there'd be less of a need to go with the buxom babes and badass Marines.