i think her leaving was to open other areas in the story, when does chief talk when she didnt make him?
what does chief have to lose? what could be sacrificed? what would make him question every thing, and have his personality show to players?
cortana being percieved as dead/gone.
how else could chief personally have something to struggle for?
not just try hard to save the world which is his duty.
the only thing that matters to him is cortana.
so they exploit events that happened in halo 3 .(the screen hallucinations)
as more then a projection, maybe she was loosing her mind…lets find a term for that.rampancy.
than use that idea , making her condition worsen, than have her state convenient facts that would force her to sound dead without hope of revival.
but after chief has delt with it, and we have seen who he really is. and his character had deepened all i can.
those who havent read the books dont know anything about chief, just his actions…
her absence would have served its purpose.
it wouldnt be a “save the princess” senario it would be a “reunion”