Ok, Blizz should install l33tness-screening portals then to screen out the scrubs who don't "deserve" to fight a boss out in the open world, setting up a world boss and expecting just the target-group to go there is (To stay subtle) immensely naive, coupling that with a "Spread out or DIE DIE DIE!!!"-attack makes it stupidity of a thusfar unseen magnitude.
If Blizz wants to do a "Heroic raiders only"-boss, stick it in an instance because (And i said this when this disaster was announced) because mixing "heroic raiders only" and "Anybody can join into an attempt in progress" in one boss just does not work!