[Stephen]

I think the bleakness and darkness of this trailer and probably the film is deliberate and once the film reaches its climax and the Justice League is formed or at least partially that things will brighten up.

For example the world is in a dark place and the world needs people to free it and make the world a brighter place.

I think the dark nature of the film is a metaphore for the situation of the world and the way people feel.

There is also a few little easter eggs in the trailer..

Biggest one I personally spotted after a few views was a very Riddler like question mark in the scene with lightning and the pillars.