What I find baffling about this gesture, and the positive response among liberals, is that it's all quite openly in the service of a modeling contract for a line of cosmetics. Winslet has agreed to promote a luxury product that allows women - quite laboriously, and at great expense - to adjust their appearance in order to conform to popular beauty conventions. She's been chosen to do this because she already conforms to them quite closely, in part by genetic luck and in part because, as Chris Rock puts it, money is the best lotion in the world. By any reasonable assessment, the beauty standards promoted by Kate Winslet, professionally made up by world-class cosmetologists, are already well out of reach of the average woman, and certainly just as capricious.
Since Winslet is promoting a cosmetics company, the problem is unusually vivid in this case - but it's always been a subtext of the broader photoshopping controversy. The issue only arises, after all, when a woman's image is being presented for public consumption. Particularly in the case of mass media, those images are already deeply implicated in the perpetuation and imposition of beauty standards well before anyone decides whether or not to use photoshop. I don't mean that in some abstract, critical theory sense, as if we are automatically fetishizing a woman's appearance as soon as we take a picture of her. Here, it's enough to point out that the women we have seen in these anti-photoshopping campaigns are nearly always professional models who only diverge from quite narrow aesthetic specifications - smooth, flawless skin, high cheekbones, wide eyes, lustrous hair, etc - by matters of degree. And whenever there is a divergence, it's always dwelled on in an extremely telling spectacle, like the racist who goes out of his way to brag about his black friend.
An interesting wrinkle here, I think, is that photoshop is by far the cheapest and most accessible way that most women have to conform to beauty standards. For this reason, it's clear why cosmetics firms like L'Oreal and models like Kate Winslet would want to discourage a culture of photoshop use, since it so directly undercuts their business plans. None of this is to say that photoshop is Good, or even that cosmetic use is bad, but simply to point out that the liberal distinction being made between them seems to have more to do with business plans than with consistent, principled objections.