There is nothing wrong with sexuality or a person being sexual in there nature when they are an adult.
The OP was talking about the dress and exposing parts of the body, not sexuality. It's a fairly modern concept that nudity and sexuality are intrinsically linked.
When it comes to kids it isn't appropriate in a public setting.
To them it is. You admitted to wearing clothing your parents considered inappropriate, even though the objections weren't because of your wardrobe's revealing nature. If current styles mandate teenage girls show a little "cheek", they are going to figure out how to do it.
That is what this discussion is about, teens wearing clothing that is inappropriate for them to be wearing in public and why there parents would possibly ever consider allowing them to wear such things. The clothing that the OP describes is far to revealing for most people to be wearing at a mall, but a teenager (most likely under the age of 18) wearing things like that is really too much.
So a 16 year old walking through the mall in her underwear is a scandal, but throw in some sand and a seagull or two and nobody notices. It's an arbitrary morality assigned by society and culture.