As mentioned before, it was a pretty quick decision to make Man of Steel 2 into Batman vs. Superman. It was such a quick decision that even Wikipedia still hasn't acknowledged it in their listing of DC Comics films. As if that wasn't bad enough, Wonder Woman is being heaped onto the pile of established characters included in the film. While it's not forcing a Justice League film into production, it's still rather unfair to bring Wonder Woman to the big screen for the first time as a secondary character. Not only does Snyder have to grapple with the continuing adventures of Superman, he now has to create a new reality for Batman/Bruce Wayne, Alfred, Wonder Woman, and possibly Nightwing (provided that's still on the table). When Marvel started their universe, they gave their major heroes standalone films to develop those characters. The Avengers only happened after all the key players had some sort of background established and an initial conflict resolved. DC is trying to make their own Avengers happen, because they're a good decade or so behind Marvel's universe. They want the $1.5 billion pay day without all the groundwork that came before it, just so they can feel they're still in the same league.