Given the title of the film practically everyone who knows anything about these characters knows that this film is going to end with the formation of the Justice League but I don't think they need to show that in the trailer, it kind of takes away from the Batman Vs Superman part.
Lets at least pretend for a bit that they are going to fight it out to the end instead of showing, oh no we made up, oh and Wonder Woman joined us. They didn't need to show doomsday either or they should have hinted at him instead of a "here look it's doomsday".
As someone else stated how about the star wars trailers making them more excited, think about it how much of the plot have we figured out from them, practically nothing. All people have are questions.