Let's be totally honest here (and realistic), and note that the gaming INDUSTRY will change for the positive in regards to treatment of women when, and only when, it's profitable for it to do so.
As a weird side tangent, how many positive portrayals of women are there in beer commercials? I honestly don't know as I don't really pay attention to beer commercials, but my admittedly superficial analysis recalls only images of women as sexual conquests (the multiple women hanging off "the most interesting man in the world" etc...). No "I love relaxing in my sweatpants with a nice cold beer after a long and shitty day of compiling code..." types. Again, I don't pay much attention so I could be wrong, but sex sells beer to a largely male audience, so the beer industry uses superficial image that appeal to the baser instincts of men. Same thing with the vidya industry. Largely male, and often a fairly young and hormonal audience at that. What appeals to them? Positive female images, or their fantasy of sexy women? Hmm...
I imagine being a woman working in the advertising industry is probably similarly frustrating.
Change the economics of the situation, and you can get them pandering to whatever is going to make them the most $. Kinda sad, but true.