So I was checking some comic related news, and while reading the articles on comicvine, I stumbled upon this image
Look at the way the characters are placed
It's obvious that not even DC themselves consider Wonder Woman relevant enough to be considered part of the Big Three.
Of course this may be just a fad, but it shows that Wonder Woman was just a place-holder for the next big thing as far as DC's higher-ups are concerned.
Something to do with Geoff Johns being DC's new Chief Creative Officer?