I will agree that Avenger's Shield will generate more threat on each target it hits than the heroic throw will on its single target however the point is that you do now have a threat generating ranged attack while pallies are lacking an ability to sprint into the fray and get solid positioning before the rest of the raid joins in the dps.
A fight where this is almost mandatory is Sapph. After your first wipe where he agros as soon as you step foot in the room. Till first flight phase, he is bombarding a the whole raid with blizzard because everyone is all crouded up at the entrance when the darn pally tank couldn't make enough ground before he was settled in his position.
Granted we still get him down... its just anoying.
Plus.... Heroic Leap would just look so awesome.

