This article is talking only about one part of the story, while it can't be denied that people demand girls to look good. At the same time, girls themselves get into peer pressure easily. Very quickly in their lives they get the feeling that in order to be 'looked at' you have to be beautiful. I am not saying that guys don't suffer from this, but girls suffer from this more than guys.

Its like the TV channels competing for TRP's. The demand for a something good exists, but the fact is that the demand is fueled by the content providers and not viewers.

Now on a larger scale, the society doesn't dumb down girls. Its just the mere biological reasons prevent them from doing so many jobs that are common for men. Women have higher social pressures, physically and biologically they have more limitations when compared to men. They have bigger social pressures to deal with. All in all, this counts for most of the reasons why women don't get the incremental learning at the same rate as men.

Now come to look at the other part of it, there is huge difference between looking good/presentable and wild chase for beauty. Cosmetic products exist both for men and women, but their nature differ. Apart from your usual set of deodorants and usual kit et al, you don't mascara or lipstick for men. Not that such a thing is not desirable for men, but its just that men won't chase it at all.

Ultimately you truly get what you want.