One could argue that, for equality's sake, if you're going to have a half-naked scene of a male character that at least has some minor point, then the equivalent half-naked scene of the female character should at least be relevant to the character development or SOMETHING regarding the female character.
But, as has already been pointed out, this isn't
Carol's story; it's Kirk's.
The half-naked shot of Carol Marcus in the film serves to reinforce the idea that...Kirk still has some issues.
But, anyway, as has also been pointed out, it does
tell us something about Carol, too. It, in conjunction with her bringing up of Chapel, tells us (and Kirk) that she won't stand for being another hit-and-run victim of Kirk's affairs. Why would that be an important point for her to make? Because she finds him attractive, just as she knows he finds her attractive, too. Everyone should have noticed that Kirk engaged the charm machine right away, beginning when they first met on the shuttle. She obviously finds him attractive too, or else she wouldn't have changed in front of him so overtly in the first place. She's interested, but she wants a relationship with a grown-up.