Now that Kate Upton has been on the covers of both US and UK Vogue, does this mean breasts are now officially in fashion?

Name withheld, by email

If only it were so simple, Name Withheld, if only it were. As you beadily note, Kate Upton – a beautiful and well-upholstered model who was previously best known for wearing near-non-existent bikinis on the cover of Sports Illustrated's deeply sporty annual swimsuit issue – was recently on the cover of US Vogue and is currently on the cover of the UK version, having previously appeared on it in January 2013. This, you might well think, must surely represent the final breaking down of the hardened wall – pretty much a Berlin wall, really – between the heretofore very separate worlds of models favoured by women's magazines and those favoured by men's magazines, worlds generally delineated by the size of the bosoms of the models.

To paraphrase one of Kanye West's few sensible utterances, when he spoke about the former President Bush, women's fashion magazines don't care about bosoms. Which is odd, if you think about it, seeing as the vast, vast majority of their readers, as well as their writers and editors, have bosoms. Nonetheless, bosoms are seen as cheap, embarrassing, even – gasp! – unfashionable, and are treated with an attitude close to distaste by many in the women's fashion business. Only the flat-chested can be elevated to the lofty status of "fashion icon" – those with anything larger than a B cup are dismissed as simply not trying hard enough. The widely disseminated excuse for this is that clothes "don't hang well" on well-busted ladies, and there is something in this. The most fashionable kinds of clothes – say, the classic YSL tuxedo or the Chanel tweed jacket – tend to look less than perfect on us bigger busted ladies. But the fault here lies not with the bust but with the clothes themselves, as to say an item of women's clothing doesn't work with bosoms is like saying an item of a human's clothing can't possibly hang well with all those pesky shoulders and arms getting in the way. Victoria Beckham might have been able to gain acceptance into the fashion world by having her breast implants removed, but for those of us who are naturally over a size C cup, that is simply not an option. Different women are differently sized, of course, but to dismiss a fairly basic part of a woman's anatomy as inconvenient suggests that too many people who work in women's fashion simply don't quite understand women.

Some fashion critics like to make the ridiculous and frankly homophobic argument that fashion's distaste for bosoms is because so many designers are gay and therefore they want women to look like men and they all secretly hate women and something, something, blah blah. Leaving aside the absurd insinuation that all gay men hate women, this ridiculous contention is disproved by the briefest of looks at the models used by the straight men who design womenswear (Roberto Cavalli, Paul Smith and Ralph Lauren, off the top of my head), and those used by female designers (Stella McCartney, Céline's Phoebe Philo, Miuccia Prada), as they, funnily enough, happen to be the very same small-busted models used by gay designers. So to say fashion's anti-bosom stance is about misogyny is simply too sweeping. What it's really about is skinniness: breasts are seen as a sign of fatness. This is not misogyny, exactly, but rather part of the fashion world's insanity about body size, which sometimes elides into misogyny, but in this case is really just about shallowness and idiocy.

So when Ms Upton and her bounteous bosom started appearing in fashion magazines, I was cheered, not just to see a different body shape being appreciated, but to see fashion editors attempting to work with it and dress it in clothes a well-bosomed woman might actually wish to wear. Upton's shoot in Vogue last year was a case in point, in which the talented stylist Francesca Burns put her in elegant, simple clothes, neither ignoring her body shape nor making a big deal of it.

But a change has been happening of late. With an almost tic-like inevitability, Upton's shoots in fashion magazines are increasingly becoming indistinguishable from the ones she has done in men's magazines and Sports Illustrated swimsuit issues. No, she hasn't yet been photographed in Vogue in a tiny bikini and sucking a phallic lolly, as she once was in fellow Condé Nast magazine GQ (stay classy, GQ!). But rather than wearing elegant dresses and whatnot, she is instead wearing bikini tops that bust open for no reason and one-piece swimming costumes that split apart. Instead of fashion magazines taking advantage of this extraordinary moment, when a curvaceous model is popular and showing readers that one can be fashionable and curvy, fashion magazines are instead, well, just taking advantage of the model's curves.

Look, it's not easy being a big-busted fan of fashion. We have to put up with vintage shop owners telling us our "tits don't work with vintage, sorry love" (actual quote) and we have to accept that we will never, ever be able to wear a tuxedo (not actually such a hardship, to be honest). But the one thing we could always rely on with the fashion world was that it wouldn't catcall us like a bunch of bored builders on a lunchbreak. But it turns out that even fashion people can only think of two things to do with a big-busted woman and once you've done one (put her in a high-necked dress) you're just left with the other (get her tits out). And that is not a strategy with longevity, suggesting that this current fascination with women's breasts is really just a brief flirtation rather than a new relationship.

Post your questions to Hadley Freeman, Ask Hadley, The Guardian, Kings Place, 90 York Way, London N1 9GU. Email ask.hadley@theguardian.com.