Generally speaking other people want to associate, befriend, and date good looking people. If they're with us then we must have "something special".
I once heard a "shock jock" in LA say if a woman looks like a "10" (she doesn't need a degree. She'll have no problem finding a man who is willing to pay her bills. On the other hand if she looks like a "2" she had better hit the books hard!) In other words she's going to have to make her own way.
As crass as that sounds I believe it does have some merit to it. Rich and successful men do tend to pursue women who are considered beautiful. Having said that the beautiful woman with no education/career skills has short window or shelf life to attract and marry a rich man.
It's also human nature to want the best looking of anything we can afford or get our hands on. If you went to the grocery store to purchase a can of beans and there were three cans on the shelf. One had a small dent on the side, another had half of it's label torn off, and the third looked like it just roll off the assembly line odds are you're going put that one in your cart. It doesn't matter their content quality is the same and all three have the same lot #.
Beautiful people are also hard to say "no" to especially if they don't come across as arrogant or acting as if they "know" they're beautiful.
Studies have also be done which showed a very attractive woman having a flat tire versus an obese woman having a flat tire. There was a major difference in the number of offers for help each of them received.
Oftentimes the front desk receptionist is a woman and an attractive one at that. Many companies view this person as the first face of the company. Good looking and well dressed people make a statement.
The higher an employee goes the more interaction they will have with people outside of the company. Having good looking executives or salespeople is seen as having a classy company image.
Lastly I believe a lot of good looking people exude more confidence mainly because they've probably received more compliments over a lifetime and yet it has been said models are some of the most insecure women in the world. If anyone points out a single flaw they'll obsess over it. Not every good looking person is confident.