I don't know man, living worlds can feel dead and dead worlds can feel alive. I much prefer a world where every NPC and prop has meaning making the world feel immersive and alive (ie Dark Souls, FFX) as opposed to large amounts of filler in a world making it feel dead (ie Oblivion, large parts of FFXII). So whether worlds are dead/alive only counts for anything if what is within them fits and adds meaning/immersion.