This is one of my (numerous) pet peeves.
In old movies, tough guys were often played by wimpy actors. It wasn't a serious problem since they were normally fully clothed. When they did, say, take their shirts off, the tough-guy swagger became laughable. Or at least, it's laughable to our modern eye, conditioned as we are to seeing tough guys played by tough-looking actors with very large muscles. I think we owe that to Arnold Schwarzenegger and the first Conan movie. Sean Connery looked tough in the early Bond movies, but compare him to Daniel Craig and he deflates.
Unfortunately, the same thing hasn't happened with female characters and the actresses who play them. Since nowadays there are more female characters who are supposed to be physically tough than there were in old movies, and since they show much more of their bodies than was acceptable long ago, the contrast between what the character is supposed to be and what the actress looks like can really mess up your willing suspension of disbelief.
I think this is even truer on TV than in movies. Battlestar Galactica is a prime example. The difference between the men and the women is striking. A lot of the actors are, if anything, too muscular for the characters they play; you keep wondering when they have time work out so much. The actresses who play fighter pilots swagger and sneer and posture and threaten each other and generally act as macha and fighter-jock(ette) obnoxious as they can. But their outfits let us see just how wimpy and soft they are. If they were lean and hard, their characters would still be obnoxious, but at least the act would be believable. Instead, it's laughable.
Last night, I watched a taped episode of The Sarah Connor Chronicles, a show I'm increasingly hooked on. The episode, "The Tower Is Tall but the Fall Is Short," was a good one -- well written and acted, and it moved the story arc along satisfyingly. It also introduced a new character, Jesse, played by Australian actress Stephanie Jacobsen. Jesse is yet another refugee from the post-apocalyptic future, a tough soldier. Now, Jacobsen has a face that one can stare at for a long time in delight, but her body, which we saw a nice amount of, is that of a wimpy fashion model. She's no lean, hardened survivor from that future guerilla army. For that matter, Lena Headey, who plays Sarah Connor and is supposed to be just as tough and dangerous as Jesse, is only marginally physically better suited to her role.
What's so annoying about such casting is that it's unnecessary. Los Angeles is famously filled with fitness babes, and I saw lots of them in Vancouver the last time I was there. Surely many of them can act adequately. So whether a series is filmed in Hollywood or Hollywood North, there's no reason for the kind of casting I'm complaining about.
Do audiences not care? Are other viewers not struck by the incongruity? Or are they so unfamiliar with the look of female fitness that they don't even see the incongruity?
(Update. Here's another example - Silk Spectre in the Watchmen comic books and the wimp who'll be portraying her in the movie. The absurdity of having her wear high heels seems to come from the comics.)
(Graphic novel: noun, synonym for comic book.)