I don't think so much that characterizations of females have changed. They have improved in some cases but I believe that it's more of the styles of games have changed. There are more dark and gritty games now than before. Everything is getting a brown tint, cause brown means realistic? And a character like Rikku wouldn't fit in in those games.
Now the strides in female characterization has vastly improved. Take the bioware games for example, they are making strides in making playable, well constructed and not very skanky unless their character calls for it, females. David Gaider, Dragon Age's Senior Writer gave a great panel/conference regarding sex in video games at
last years GDC. It addresses females and the sexualization of it and how that's just lame. He addresses the Game Developers as a whole in it. It's a great listen/read.
Anyway, it's an uphill battle to include female protagonists and will be for a while because it's breaking down the whole "games are for boys" stereotype that many developers still have problems with.
Check out our former Editor Raistlin's
Sexism in Final Fantasy article series.
Because even FF, even after they made Lightning be the hero, they still had to make
her boobs bigger and gave her a
cat outfit. Sorry SE, that's defeating the whole strong female protagonist without skanky fanservice thing. Those are all things we've personally reported on.
So yes there has been a change but it's more because of the games. But there are still large steps into making it the other way that they create them because strong females are the reason.