She's also a Mary Sue that most people love anyway.
Sane Person: Why? You want to be a shallow, two-faced bitch?
Essentially perfect and lacking any sort of flaws or personality, as to make her easier for teen girls to identify with, though, in reality, it just makes teen girls focus more on Edward Cullen, driving the popularity of a shitty book even higher.
SmartPerson: "You want to be a klutzy whiny bitch?"