Because let's face it, everybody hates themselves at one time or another. I sort of imagine this when she's about fifteen or sixteen. Reviews are greatly, greatly appreciated.
Hinata wishes she were beautiful.
Oh God, how she wishes for it.
If she only had the big blue eyes that Ino uses to get her way, if she only had the long black lashes that Sakura takes pride in. Maybe if she had the curving lips that Temari paints in rich red dye of cherries, or the breasts that Tsunade had dominion over. Maybe if she had her hips or her eyes or her oval face or her perfect hair, she would be beautiful.
Hinata doesn't realize that if she had these features how mismatched she'd be, like a little doll stitched together and trying too hard to achieve perfection, which isn't even a possibility in this world anyway.
She's tried different hairstyles. Different clothes, different bras, different hair colors. Eye contacts, different shades of lipstick, fake tans. She can never find a way to capture the beauty she admires in another.
So, she decides, she'll settle. She'll live with her small breasts, with her overly thin, fragile frame. She'll live with her too large, colorless eyes. She'll live with her too pale, china-white skin, with her purple-plastic colored hair. With her stupid fat lips and her undefined nose. With her short little eyelashes.
But it always lingers in her mind. Maybe, if she were beautiful, she would be loved.