Mikel stopped by to explain what happened with cover:
As I’ve already explained (a week ago in my blog), it was not an editorial choice to make her show her cleavage, but to match the interiors. The solicit cover was made BEFORE the series, and this corset appeared solely in issue #1. Then, Zee’s look has been slightly different in each issue, with black corsets, white corsets, black jackets and so. I’m sorry if someone is offended but there’s not any intention other than match the interior pages.
Best regards!
And indeed Zatanna is wearing that outfit, among others, in book:

OK. Let me put a couple things aside first: 1. I never really got on board with a LOT of the New 52 redesigns. I could...
I’m fine with the cover being made...match the interiors…I’m not fine
Still miss the stage magician look.
It’s still dumb.
Still growling, all the same. :\