While I agree that Barbie can present an unrealistic example, this old saw really doesn't hold up under scrutiny. In your presentation, you've scaled up the body but you haven't scaled up the clothes.If Barbie were actually 5'6", then her clothes would also be six times as thick, not to mention the difference in how they'd drape. The doll is made thinner to compensate for the fact that the cloth can't be. Yes, even correcting for that it's still uncommonly thin, but not quite so grotesque as this argument suggests.
1) I didn't make this graphic myself. But, more importantly, the reason I linked it here is simply the grotesque that the photoshop attempt to show "to scale" seemed very revealing from a visual perspective. Thinness aside, it is compelling to me to look at the head side and shape, the overall silhouette as it applies to scale of specific features. What they didn't alter is as pertinent here as why they highlighted.If I were making a diagram I would get extremely hung up on the "average woman" figures, which is in no small part why I haven't bothered to make a rigorously studied image of my own. The arguments about "average woman" can and do take up a plethora of blogs unto themselves. I find looking at the picture that it points out most profoundly where the woman and Barbie don't match up in neck length, head width, and other features that are frankly far more pertinent in some ways than waists. You can talk about bust, waist, hip ratios till the cows come home, but for girls, you're looking at one another face to face. I'll go ahead and make an argument that creating a doll that for young girls then spending more time thinking about the aesthetically sexual components of their doll than the points that apply to perception in everyday interaction is doing missing an important overall point. Also, if you want to get into an argument about how Barbie's clothes would drape... well, we should do that over drinks because I have OPINIONS about fabrics, mannequins, dolls and the back and forth of those motivations. Short version, anyone who uses plastic cloth as a budget-cutting step, not a sartorial choice is probably going to hell.