For the most part I agree that the term itself is riddiculous. We're gamers, not boy gamers and girl gamers, however I can understand the need to use some kind of term when speaking about issues like discrimination towards players based on their gender. I don't play online myself, and thankfully I have not been patronized by staff members when going into game shops (mostly because the game shops over here have both male and female employees) - however I've heard enough stories to know that this is a problem that needs to be adressed.
The term "girl gamer" is unfortunate and has been warped (by images of girls trying to look sexy while handling some kind of gaming hardware) to such a degree that it's rejected by the majority of the gaming community, males and females alike. I don't use the term "girl gamer" to describe myself, despite being a girl who likes playing games. Firstly I don't think it's relevant to point out my gender, it's usually clear as day that I'm female as I tend to have feminine usernames, but I don't elaborately point out my gender (not unless it's relevant to the discussion, like this one).
Firstly I don't want my fails and victories to be contributed towards my gender. If I am good at something or suck at something, it should be about my type of gameplay and skill, not because I happen to be female. Same goes for what types of games and gameplay I like and don't like. Even though it fits the stereotype that I personally have no interest in FPS, it shouldn't automatically be linked as such, as there are plenty of girls out there who do enjoy FPS. Nor should it be a "whoa" revelation to learn that I enjoy combat and skating games. My gender doesn't dictate my interests, same goes for everyone else. Sometimes we like things that fit the stereotype, other times we like the complete opposite.