Great question — answering as the UphillTech team:
As all stereotypes, it's an oversimplification. Our culture is focused mainly (or almost exclusively) on the material, so the "important" traits are physical: strength, beauty, knowledge/intelligence (often wrong intertwined), money, power,... This, being still too complicated for the pop culture, is simplified further: power means money, good physical traits will give you both (at least by the end of the movie),... so, you're left with body and mind as the only two important traits (now my answer is a bit of an oversimplification, but not as much). Another simplification is that pretty = sociable. So, those not pretty are not sociable, which is the reason why such persons become, as you...
Full answer by Vedran Šego: https://movies.stackexchange.com/a/14079 (CC BY-SA 3.0).
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