You type that like this is not one of the first image results for Nightwing.
This has been around since 41, and it is not going away. The 90s had more focus on showing skin. Today puts more emphasis on freakishly tight clothes even with costumes like this that highlight breasts and are designed to look like bras.
This era of comics will be known for its very sexualized heroes like they all are.
I can name many heroes (male and female) more sexualized than Power Girl. The only difference is her creators do not deny it.
And people know Black Canary because of her fishnets above all else. This is not unique.
Behold her first appearence.
As this full answer from our resident expert describes (it is lower on the comment) that is a myth. It again simply shows that Power Girl is just upfront about it.
No they do not. You better not come after my gym shorts next. It is canon that I made my costume to make boys look at me. Why does nobody talk about that?