Barbie-maker Mattel is a business. As a business, Mattel is responsible to its shareholders to make as much money as they can to provide a positive return on their shareholders' investment. Entertaining children is big business in a highly competitive industry. Depending on their age level, some kids are more entertained with the box their toy was packaged in the toy itself. So, Mattel owes it to their investors since there are many ways to entertain children.
Yes, the toy maker should focus on share price more than entertaining children, because that is their job if they are a for-profit company. You don't buy shares in a public company hoping the company will entertain children. If they were a privately held company they could do what they want, but since they are not, they need to maximize profit.
Toy makers should focus more on entertaining children, and less on share price. By producing quality, fun toys for kids, toy maker share prices will rise appropriately. By forgetting their core competency of producing quality toys, toy makers may lose sight of the fact that producing great toys is what actually gets their products to sell, and therefore become profitable.
I think if you were to focus on share price more than entertaining children or vice versa you are ultimately going to end up with the same problem. If you focus too much on one side of the coin the other side will struggle and eventually cause both to faulter.