I came across this blog post someone made back in November regarding what Warner Bros' actually approach could be in relation to Marvel's. For a while now I was thinking along these lines but this post actually puts into words what I was thinking. Here's the link to it for those interested.
http://www.sixokay.com/2013/11/23/man-of-steel-isnt-about-superman/
The basic idea is that Man of Steel wasn't and possibly after the fact isn't about creating a new Superman franchise, following the pattern Marvel established with Iron Man, Thor, etc but primarily about creating an all encompassing Justice League movie franchise or brand. Which results in WB/DC having movies that focus on a particular storyline that builds the universe and not a particular character for the character's sake. That might give them the freedom to add and subtract characters as they choose from movie to movie based on the story.
The example used in the link is how Justice League Unlimited and Brave and the Bold operated. Where you might have a story focusing on Superman (Man of Steel for example) then the next as we now have focusing on Superman and Batman with some Wonder Woman sprinkled in. The film we are looking forward to now. The next could be Flash and Superman or Batman along with the rest of the Batman family. Then leading to a Superman/Batman/Wonder Woman/Flash story or a Green Lantern/Wonder Woman/Flash film. That still leaves room for them to focus on Batman again if they choose but they won't have to as this allows them to diversify to a point.
Pure speculation but something I've been thinking about myself. Especially in light of Snyder saying that the world in which this universe has been introduced, tone set, they can pretty much go wild with what they want to show and do. Comments like that and them going right to a Batman/Superman film with a Batman already established shows they aren't following Marvel. Doesn't mean they're rushing things. It might be more conservative and safer for them to also team up heroes more then risk solo failures. Does this mean they might not have faith in characters. Sure but there is a lot of money at risk and better to have some assurances in place. Especially since, and this is also brought up, that Warner Bros does a LOT of other films and not exclusively superhero films like Marvel. They don't really have the money or time to devote to these films the way Marvel does. So whatever time and money they devote to this has to be used differently and with a different goal in mind.
This a crazy thought?
