Steph, that reminded me of a service I heard of on NPR that allows you to submit your vacation pictures and have them professionally photoshopped. I don't just mean routine teeth-whitening, waist-slimming sort of photoshopping, but they will actually photoshop images of celebrities into the picture so you can lie and say you met them! Doubt that it's very effective but still ridiculous.
Anyway, I think the sad truth behind Kelly Clarkson's photoshop job is that there is a high probability that fewer people would buy it if her un-photoshopped body was on the cover. Everyone says they want to see "real" women on magazines and in catalogs, but I suspect if that were actually implemented, we might find that it has the opposite effect. In this case, women will see a skinny KC on the cover and want to learn more about how she maintains her body. If they just saw some woman who looks exactly like they already do, what's the point? I'm not condoning this or anything, just trying to acknowledge the sad reality.