Obviously they don't have dialouge for a reason. A lot of people are going to dismiss this story as just another camp fest comic book movie. The point of this teaser is to get people's imagination flowing bout what exactly could this movie be? Then they visit the website and they can find out more about it. When a person reads it they might be bound to be more intrested in it, then if they are trying to pick out a plot from a narraration. But just keep in mind that Rorshach did set up a bit of a narration by saying when they look to the sky and ask for help, ill whisper No. it kind of gives the veiwer an idea, that something is happening.

Watchmen
Trailer
(2:20)