Threat has been a joke for the entire expansion, and now Blizzard announced that threat management is removed from the game.
My initial reaction was that it's a horrible change, but then I sat back and rethought my position.
Threat has been a joke for the entire expansion. This is the key fact. It is also not entirely true. Threat has been a joke for the entire expansion, apart from the first fifteen seconds when you play Russian roulette with your party/raid. After all, taking zero damage should be the holy grail for a tank, but if you take zero damage, then your target will have your companions for dinner.
So, in reality this change makes the likelyhood of you accidentally blowing the head off your friends less likely until you reach the point where threat didn't matter at all before the announced change. Threat was already binary due to a poor implementation of Vengeance to begin with.
Still, there will be complaints. An immediate stack of one third of the taken damage from the first attack. PvP as a tank suddenly became a lot more interesting.