All explained by signalling theory - signalling status, which is useful for survival of offspring. That's what I mean by it isn't arbitrary. And it isn't all about wealth, either. Walking in high heels proves a certain level of fitness, for example.

And most things that are seen as attractive in women are simply signals of youth, as young women can have more children than old women. You can't remove that with socialism.

As for descriptions of women in Victorian society, they may just be caricatures, or something like modern fashion photography might be going on - the women displayed in fashion photography (artificially thinned) are not actually the ones men find the most attractive. It might be more of an intersexual competition between women. And again status - in our world thinness proves status, because it is difficult to be thin. In scarcity worlds, some fatness proves you are rich and can afford to eat.

(Peacocks signal with their tails that they are healthy and strong, even though they have no society they live in, so no inequality and class struggles).