Snyder said the following to the Japan Times:
I wanted the movie to have a mythological feeling. In ancient mythology, mass deaths are used to symbolize disasters. In other countries like Greece and Japan, myths were recounted through the generations, partly to answer unanswerable questions about death and violence. In America, we don’t have that legacy of ancient mythology. Superman is probably the closest we get. It’s a way of recounting the myth.
A few things. One, mass deaths don’t symbolize disasters — they ARE disasters. And the “unanswerable questions” that myths once tried to answer are now mostly, well, answered. So myth has a different role now than it once did. (We know, for example, why people die in Man of Steel. Because: punching. And because Superman never takes the fight elsewhere.)