At the risk of using tropes on a month old comment, I believe the reasoning is a combination of "innocent fanservice girl" and "even the girls want her".
Why do Kazami Yuuka's and Yasaka Kanako's gym shirts have their personal names on the name tags while Yagokoro Eirin's has her surname?
Come on, you say that, but if you're not careful...Eirin's on the Other Team TooYagokoroWhy don't you take that off?Kanako...you'll get heatstroke!!Noooooooooo!!!FLAPFCome on, Kanako-chan.Eh? No, I'm fine as-is.Wait! Whaa!?Yuuka