You're bothered by this? really? I thought I knew you better than that.
You grow up with another girl, and you're both ugly ducklings in a certain way... she's too fat, you're too thin, and you kind of tease each other in a brotherly way, get in fistfights, whatever. You're similar enough that you get mistaken for each other, or at least she gets mistaken for you once in a while and you both snigger. You've got pretty much the same interests. Close enough, anyhow. Neither of you have ever understood dressing up or really looking pretty, and that's comfortable, because at least there's someone else. You can laugh together about being bad at cooking, sewing, romanticism, everything that you're "supposed" to know. You can joke about how your ankles or her right forearm are your best features. She laughs at your calculating nature and you poke fun at her airheadedness. You are equals.
You grow up and it turns out that you're the one who still practices swordfighting and eschews makeup, is terrible at cooking and can't sew or knit for beans, is tentative about and frightened of kisses, dresses like someone stereotypically would in Soviet Russia. You're still living "outside the world." Your right thigh is covered in chalk stains and you still run into furniture and stutter... you've still never worn jeans or high heels, and you continue to evade calls for cut hair or pierced ears. You still believe in a sort of chivalric code. A pessimistic idealist, obsessed with order and understanding. You don't have your cell phone number memorized. You don't own an MP3 player--nearly ubiquitous at all ages in your own home town.
She does none of these things, of course. She is contemptuous of them, now.
And now she's on Their side, and she's making fun of you the way she used to when you were the same. But you aren't on the same side anymore; things are imbalanced. She makes fun of you for the same old things but she's no longer making fun of herself, a girl who is now polished up and lauds herself for it.
So that's why it matters. It's a case of her, not a thing that simply annoys me because it exists.