Why is there a choice to be either human or vampire at the beginning of the Daybreakers DVD?

It is probably just something interactive for the audience and sets the atmosphere, or if you would like to go into theories it could be a way to separate people into groups by "asking" a simple question, creating a harmless feud/provoking a debate or invoking fear- to choose between what you know and what's comfortable: life (Human) or the unknown and are you strong enough: death (Vampire). No matter what you choose, both humans and vampires struggle to survive in the movie, so it could be that the choice forces you to "favorite" one or the other, but by the end of the movie, you will realize that both species had it rough.