This was brought to my attention a few minutes ago.

I’m not really getting involved in anything DC Comics anymore since DC ruined Harley Quinn with New 52, but I do have some thoughts on this change.
Before I get started, I want to note: someone informed me that Power Girl is wearing the S here because of a big spoilery event that just happened. The explanation behind why she’s wearing it makes perfect sense to me.
Okay, that said, I have mixed feelings. I know why a lot of people want the boob window closed. It’s seen as a very egregious symbol of sexual objectification toward women, because it was created for that purpose. No way around it, that’s why the boob window exists. For people to ogle. One of the key things done with her when she got started was the artist slowly increasing her boob size to see if anyone noticed. All the explanations for what she has a boob window (at least that I’ve seen) have been stupid.
However, I saw nothing wrong with it, really, for the same reason I’m fine with Quiet in Phantom Pain, Bayonetta, Juliet Sterling in Lollipop Chainsaw, etc. There are characters that I think can be fanservicey as long as the fanservice fits who they are as characters. You can’t have a female character opposed to the display of breasts herself displaying them, after all.
However, I saw nothing wrong with it, really, for the same reason I’m fine with Quiet in Phantom Pain, Bayonetta, Juliet Sterling in Lollipop Chainsaw, etc. There are characters that I think can be fanservicey as long as the fanservice fits who they are as characters. You can’t have a female character opposed to the display of breasts herself displaying them, after all.
My overall view is that if the boob window will be kept and attempts are made to justify it, then the simple answer is to follow the pattern of women that want to de-sexualize women going topless in public and make it the same as if men do it. It can be a symbol of resistance to social pressure on women to police their bodies for the sake of others. As long as it’s written well and respectfully, the boob window could be more of a feminist symbol than a symbol of male objectification.
I’m male, so ultimately take this suggestion with a grain of salt. It’s just my thoughts on how the existence of that boob window can be justified as something more than pandering to perversion.