Only thing I could think of after reading this was: “HA!” Honestly, they are basically removing threat to the point that mobs will stick to the target that hits them first (two hits, it seems). This same mechanic exists in the first Guild Wars: Mobs sticks to the target that hits them first for a while (then go to the target with the least health, which I learnt after the GDC 2011 panel, when they were talking about Guild Wars 2).
This kinda reminds me of my old days of tanking in WoW, when you had to chose between survivability or threat. A smart tank would mix stamina gems and strength gems (for paladins — my case — and warriors) or they could go dumb and put all stamina gems. Now… seems you’re all for stamina, no matter which class you play.
With threat removed, what next? I bet healers will get more utility and tanks and DPSes will get more self-healing or some sort of group healing — like all paladins now have access to Holy Radiance (and druids have that AoE heal).