
She was raised to be devoid of emotion right? From what I’ve seen of her backstory* she wasn’t given a whole lot of agency when growing up. She had to feel nothing because otherwise Trigon would take her over in some manner, use her for evil. The way I’ve interpreted her upbringing is that she didn’t get to make decisions about anything – she was kind of an automaton. When she was brought back to human society she had to learn how to be human again, and suddenly learn how to take choices, have emotions and grow into her own person. Without emotions I don’t think you can truly have a character.
So if she wasn’t give any choice growing up, if she had to be obedient and quash her emotions and do only what she was told without questioning, then that means that someone else has picked out her costume. A rather sexy provocative costume with thigh high boots**, cut away gaps at the side of the torso to show the breasts (sometimes), and all in all is rather skimpy (excepting the cloak of course). Now someone else choosing to dress a teenage girl in that way is pretty exploitative, especially when the girl in question probably doesn’t really understand what the style of dress means.
The fact that she kept wearing it is also rather creepy, because when she came back into human society she would have been rather innocent of the world, and now she’ll have half the blokes and lesbians on the earth leering at her. The fact that she can feel emotions and all means she’ll have an idea of what people’re thinking, which can’t be pleasant.
It reminds me of that issue of Batgirl where Babs takes Cass on holiday and gives her a tiny skimpy bikini to wear. Cass can’t deal with it because she can read the body language of all the blokes and see what they want to do to her. At least most of us can ignore or may not notice sexual harassment on the street, but if you can read body language then it must become really oppressive and aggressive.
*My knowledge of her backstory comes from the current Teen Titans run, so it's quite likely there's a lot I don't know. If anyone would like to fill in the gaps That's be much appreciated.
**I know she doesn't always have thigh high boots but when artists change the costume for one issue, without an in context explanation, I get the idea that they are intending that version as the definitive costume, so for the current issue you can just forget about past options.