Young men and women (teens) often dress outrageously as an act of rebelling or finding their identity. This is quite normal and healthy. Copying their peers is also quite normal.
Suggesting that dressing a certain way is not protecting yourself from male predators is wrong. People should be able to dress how they want and never ever be blamed for the actions of another.
Who defines decency? Why is exposing a part of the body indecent? Continually telling people to cover up parts of their body suggests 'shame'. people should feel free to wear (or not wear) whatever they want and not be judged by others.
Exposing 'body parts' is not a symptom of low self-esteem; it could actually be a sign of self-confidence.