I don't have a whole lot to add to this, but I would like to respond to Vector's insistence in the lack of strong female roles in television. I won't deny that positive female leads are a bit hard to find in TV, but I think you might have too narrow an experience. How often do you watch trash prime-time sitcoms? Everybody Loves Raymond, King of Queens, Two and a Half Men, just to name the largely successful ones, nevermind the legions of shit most people here would never think to watch.
In every single one of them I can think of, the only negative character traits ever attached to the main female characters are maybe a harshness of attitude. But across most of mainstream television, it's essentially taboo to overtly make fun of any one woman or women in general, except for token stuff like shopping that's been run into the ground anyway. I don't know when it started or exactly why, but it's hard to find a prime-time prime-network television show, sitcom or crime drama or anything else really, where the female characters of any establishment aren't intelligent, rational, courteous, and put-upon, while their male co-stars (more often main stars) are at best idiosyncratic and flawed, or meat-headed schlubs lucky to have the company (and no really explicable reason).
I certainly wouldn't deny that there's a problem in that. If anything, the trend I can see in television of almost all stripes is the female characters are largely empty, devoid of negative traits but possessing only the most general of positive ones as well, and more often defined by their professions or role in the story than by their own personalities. If nothing else, being set-dressing is better than an object of gratuity or ridicule, but it's still a shame and a crime against good writing to be sure. I can think of TV franchises that had well-developed female characters, but there's not many and that fact itself is part of what made them so memorable. But I still wouldn't say that mainstream television depicts women negatively.
As for "diversity" of races and genders in media in general, they are more than just physical characteristics. Bemoaning a lack of female characters or black or whatever is not the same thing as bemoaning a lack of tall people. We recognize the presence or lack of different races and genders in a story, precisely because race and gender have such wide ramifications in the real world, that two characters identical in all ways except race or gender tell two subtly but fundamentally different stories, at least to anyone who sits back and tries to imagine the backstory. (That said, I do object to characters who would never have fit into historical narratives - the abundance of single token black characters in WW2 movies grates me every time).
And I'm all for pointless, never-commented-on diversity in children's programming. Why? Because blase non-issue of diversity is a good thing to teach people while they're impressionable, and it costs the story nothing to change up the characters a bit.