i think people do this because they are shallow. they judge people before they even know them. just because they aren't a barbie doll or ken image person. people can't seem to look past their eyes...i try to look at a person's character. cause that is what a person should be judged by.
Guys like girls who look attractive. Women actually need security and look are not as important. Nevertheless, the personality maybe nice. But ultimately, people will need to have sex in a relationship, and they don't want to puke when they are with their partner.
Because physical appearance tells us a lot about a person in the beginning of a relationship.
Things like the persons health and genetics seem to be a top priority when it comes to how males select.
Personality is very important too, I would say the most important, but it takes a great deal of time to really get to know someone and guys have to work very fast in order to keep their options open :)