Objection why do you consider "looking sexy" to be something that women are supposed to aim at? I am not a sex worker, so why on earth would "looking sexy" benefit me in any way? I have one DH, I do not want another one nor an affair, so while I might wish to look attractive, presentable, smart, etc, on a day to day basis I really couldn't give a fig about "looking sexy".
Neither do I especially care about what men find "sexy" in women. For the reasons above, and because I am not a man.
More and more, I suspect this type of thread is written to make the writer and certain women, who are not considered conventionally attractive, feel better about themselves. The subject of their derision is a model, she is a damned sight more attractive than most of us (certainly more so than me), and makes a living out of the way she looks, which again is more than the majority of us will ever do. Gosh you can see her ribs (perfectly normal in a healthy adult) and some muscles (again, normal). And gosh again she is tall and lean.
Good heavens - a few men somewhere in the world might not find her to her taste. Most men wouldn't get anywhere near her, and probably make negative comments to make themselves feel better about it, rather than genuine ones. I bet she's not losing any sleep over it.