It all comes down to the kid feeling a need to have the attention drawn to him or her. If the parents were doing a half decent job of nurturing their kids, they wouldn't feel the insecurity they obviously feel and would not need to dress scantily to attract attention to themselves. And yes, I have a preteen daughter and a teenage son so I know of what I speak, lol.
My mom said "no" a lot. Esprit and Guess were really in when I was 11-12 years old. Later, Express and Gap clothing was de rigeur at my high school (this was over ten years ago). My school adopted a draconian dress code when I was a junior in high school. Girls could have pierced ears, but boys couldn't. The only people allowed to keep their nose rings (not very common in 1991) were the kids who already had them before then. Boys' hair couldn't touch their shirt collars. If you were a girl, your skirt had to be at least one inch below your fingertips when you held your arms straight at your sides. Midriffs were not seen; our cheerleaders' uniforms were quite modest, and our drill team wore even more modest uniforms. Even jeans with frayed hems weren't allowed. You couldn't even wear sandals without socks. We complained a lot, but at least we looked respectable. Then again, slutty clothing was not nearly as trendy in the early 1990s as it is now; when I was in high school we went from late 1980s preppiness to grunge to 1970s revival, which extended to bellbottom pants but NOT miniskirts. I can't believe some of the crap girls nowadays wear.
I was shopping with a friend of mine yesterday. She has a four month-old son, so we went looking for baby clothes. The store we were in carried clothes for children up to ten years old and we lingered in the girl's section for some reason. We were absolutely shocked at some of the clothing we saw on the racks. Midriff-exposing tops in sizes down to 3-4 years old. Tight dresses from age 2 onwards. Padded bras and dress tops. Low-cut tops and dresses. T-shirts with messages like "Sexy Bitch" and "Spoiled Brat" on them for girls as young as eighteen months.
And this was a respectable national chain. I complained to one of the saleswomen on the floor, saying that I didn't feel that they should be carrying clothes like that for extremely young girls, but she just shrugged her shoulders in response and said, "That's what sells."
I weep for the future.