Basically to just maybe pickup a second or third extra mob or an add right next to the boss being taunted. Clarification, I'm not asking for an AoE taunt of any kind, but tank don't contribute any real damage. Each point of the small amount of dps they do get out should also increase threat by some factor. Maybe this can go into the final tier of heavy armor passive. If there is no 'threat point' system in this game there could be a passive taunt on all targets being damaged by the tank as long as the tank is doing some damage.
It probably wouldn't hurt to have single target active taunt jump to 2 other near by targets within, say, 8m of the original target.
Some kind of change in this direction would be good; the taunts should give a little more enemy NPC control in a fight.