It's because, until a daughter is married, she's still considered to be a girl by society at large. I know women here in China who're unmarried and in their 40's who think they're girls and still watch cartoons etc. This is China and it's their way and while I don't agree with it, it's not my place to comment further about it.
Because that's chinese society want them to be like.
Cute, listen what dad say...why do you think so many chinese men in mainland or taiwan go to vietnam find a spouse because they cannot find it in china? in fact, in chinese cities, men/women ratio is near 1/1 , but the mentality is very different among young girls. that's why many young taiwanese men cannot find woma, and so for the mainlanders.
Have a look n the magazine, on the young stars, singers, actress, adevrtising, all this show you how chinese society see the women.