Stick with me, here.
The standard Barbie doll had a redo several years back, where her head size was increased. It was a subtle increase, but (especially to old-school Barbie collectors like me and my sister) it was noticeable.
Bobbleheaded Barbie and Old Normal Barbie
I assume that Mattel made this alteration to follow the general "bobblehead" fad in dolls, as evidenced in Bratz, My Scene, etc.
Now I read in bnjammin's blog (referring to this LJ post) that companies are doing the same thing with reproductions of famous art.
See? The statue reproduction = bobblehead
Why has the bobblehead become our aesthetic default?
It might have something to do with the fact that even after heavy dieting, the skull remains the same size. Which is why I recommend a good headshrinker.