Why is pretty so important?

[Haruhifan]

Hiya Janey, hoping things are well on your end and you can get to this whenever you're free.

This question came up after reading the article about the ups and downs of the Olympics, with the latest story (other than for us in Canada that we suck and shouldn't even bother sending athletes to the Summer Olympics), that the little girl that sang in the Opening Ceremonies was pulling an Ashlee Simpson/Milli Vanilli in China, lip synching.  Now she is an 11 year old that was actually brought in last minute for the actual 9 year old that sang the song but had "not straight enough teeth" as the article notes.

http://www.sportsnet.ca/olympics/2008/08/12/beijing_opening_deception/

Now it's nothing new to lip synch (hence the references; I also did some in high school for a competition where all entries lip synched songs while doing choreographed acts, and we won the city championships for it) nor was it old hat (some noted it during the Ceremonies), but it does setup my question for Ask Janey.

Why is being pretty so much more important than any other trait it seems with humans?