The sentiment of One Direction’s new song is sweet, on some level, but disturbing on another. Romanticizing the ugly duckling is also nothing new; it was the point of “Sixteen Candles,” “Pretty in Pink” and “The Princess Diaries” before it became the province of today’s young heroines, Bella of “Twilight” and, to some degree, Katniss of “The Hunger Games.” But there’s something a shade different about those latter heroines, and of the girl in the One Direction song. Being underconfident isn’t just one of their traits; it’s the core of their appeal. Their stories don’t require them to find beauty within themselves, as Lady Gaga might preach.