It is, in general, much easier to sell a person something they already want than to convince them that they really want the thing you happen to have on hand; the article notes explicitly that the guy was convinced he should make Bratz after his daughter liked a prototype.

Chimpanzee girls play with dolls (chimp technology isn't quite at our levels, so their dolls are just sticks they found).

As a side note, one thing that somehow saddens me is modern Chinese terminology for dolls. 娃娃[wa wa] is a word for "baby" (how they got the idea to refer to babies as "wa wa", we may never know ;) ), and is also the standard word for "doll". A traditional doll is referred to most explicitly as 布娃娃[bu wa wa], "cloth doll"; it's the kind of doll a little girl might make for herself out of some spare material.

The term for a nice doll, the kind you'd buy in a store? 洋娃娃[yang wa wa].

"Foreign doll".