[per loin]

There was an interesting experiment done a while back in which computers were used to meld large numbers of faces into a single one. Researchers found that the larger the number of faces melded into the one, the more attractive that one was perceived to be by those viewing the face and comparing it to others.

[StriperSniper]

the larger the number of faces melded into the one, the more attractive that one was perceived to be

It averaged out the 'exagerated' features some individuals have. The resulting face would have to be more proportional and thus 'more attractive'. I'm sure the same would work within each individual race (at least to others of that race).