well the reason for switching back and forth is to fill in more of the story.. i dont know how they would of showed how the elites being ( de trowened ) by the higher arcs and the brutes.. but in the first halo when master chief blew up one of the halo's the elites were blamed for it.. so the higher arcs replaced the elites with the brutes to be there protectors.. and so much more just, just , cant go on..