To me, the question "Why didn't you do it like those other people did it?" provides its own answer. The fact that Marvel did it one way is the best possible reason for DC/Warner Bros. to do it a different way.
I don't think it's even a case of 'Marvel did it this way so they must do it a different way.' I think it's simply a case of do it whatever way works best for them and the movie. That could be the Marvel approach, could be a different approach.
Either way, looking over their shoulder at Marvel, whether to imitate or to make a point of acting differently, seems to be the wrong way to go.