Most average girls think they are ugly so they develop a really awesome personality and become smart and nice. Not saying ugly/pretty girls don't have personality's or aren't smart, but average girls seem to become beautiful the more they mature.
If anything, I think average looking girls have less hassles than ugly or beautiful girls. Since we're average people won't usually call us ugly or look down on us for our looks. And since we're not beautiful we don't have to worry about people using us for our looks or not looking past our looks to appreciate our personality as well.
I don't think there are any hassels for average looking girls. I think being beautiful is overrated. They don't have it easy those girls they take a lot of crap from both sexes. Whereas, average looking girls are treated fairly.