Also, the argument that Barbie isn't realistic doesn't make much sense. We exaggerate almost everything for kids to make it easier for them to understand. E.g. moms speak to their kids in what academics call 'motherese', to make it easier for them to pick up on the syllables. Kids get dressed in gaudy colors that would look ridiculous on adults. And they get fed foods with super exaggerated flavor profiles, e.g. ketchup. All of this is because children's senses are still developing.
So I don't see why it's surprising that popular children's toys would represent sort of the platonic ideal of the human form. In reality most people's calves and hips do flare out to some extent, so it makes sense that those sorts of features would be accentuated when reduced to toy form.
The effectiveness of motherese is a matter of debate, since it is not a cultural universal. There is a lot of cultural variation with the other simplifications for children that you mentioned.
It works for dogs too. Universally, a slightly higher pitch is used when talking to puppies. The dogs learn that higher pitch is for them an so pay more attention when hearing it.
On the recorded lectures from Robert Sapolsky, he talks about motherese being both about teaching language and expressing emotion. The aspect of language is absent when people "talk" to their pets.
Most people whose eating habits I've observed over a long period (i.e. my family) use it much less as adults than they did as children. When I was young I dutifully glopped it onto all the traditional foods. Now it seems kind of gross: cloying sweetness with a hint of tomato sauce, and it kind of smells like cough syrup. Sweet is fine, and tomato sauce is fine, in the right dish. Neither of those flavors are appealing straight out of a medicine bottle. All the kids I know consume mass quantities, but most adults have more sophisticated taste.
Kids use it more sure, but most adults still eat ketchup, just on certain dishes like fries for example. That children over do something doesn't make it a child's food.
> [ketchup] counts as a vegetable in school lunches...
That is a myth. The truth is fairly complex but boils down to that one agency briefly proposed adopting rules that might if adopted have allowed things like pickle relish to "count as a vegetable" in certain contexts.
Ketchup was not explicitly listed in the proposed rule and the rule never took effect so we'll never know how local authorities might have used that bit of new flexibility.
TL;DR: Ketchup has never counted as a vegetable.
(Salsa, on the other hand...)
We exaggerate female proportions so that they are better recognized as female by children. This is true of cartoons (barbie is essentially a cartoon person) TV, film, advertising, even music. When you want to sell something to a group you adopt an image which leaves little room for debate.
This holds true for male dolls too. I saw a great interview with Mark Hamel once about the evolution of Luke Skywalker dolls, which are now more WWE than a realistic portrayal of his character.
I wouldn't say that we exaggerate, we give recognizable symbols. For example, in many cartoons, female cartoon characters have eyelashes drawn on their eyes to distinguish them as females, children and adults alike. Now this actually makes no sense because men naturally have thicker eyelashes, and what those eyes were originally supposed to represent were mascara, but then it caught on as a recognizable symbol for being female, despite having no basis in reality. And it's crazy how effective it none the less is.
The eyelash thing is part of the larger phenomena of cuteness. Mammals, be them human babies or puppies, have larger eyes in relation to their heads. It's one of the things that identifies them as young. Women use makeup to draw attention to their eyes, to make them appear bigger and therefore more youthful. So while men may have thicker eyelashes, it is women who generally accentuate their eyelashes, resulting in the social convention that any cartoon with drawn eyelashes is female.
Look at the animation in Archer. Lana and Archer both have thick eyebrows, but Archer doesn't have any eyelashes.
Well yeah, I wasn't trying to claim it came out of nowhere. Just that the convention broadened to such a degree that it didn't make sense anymore, but we still understand it because humans are all about symbols.
> We for sure don't feed kids corn syrup and dress them ridiculously because their senses are still developing.
In some senses, yes, we do. Children often like brightly colored clothes (and objects in general), or clothes with large, obvious representations of things they like.
Foods with strong uncomplicated flavor profiles also go over well. Mac & Cheese, Chicken tenders, etc.
So I don't see why it's surprising that popular children's toys would represent sort of the platonic ideal of the human form. In reality most people's calves and hips do flare out to some extent, so it makes sense that those sorts of features would be accentuated when reduced to toy form.