This may still be the case for WAR when Alex raid comes out, but Unchained was about maximizing your damage during certain periods in boss fights, which is excellent because it allows you to stay in tank mode while dealing very respectable amounts of damage.

However, Unchained may lose it's overall value due to the addition of Deliverance. Probably not in raid settings but I will tell you this, in the HW dungeon Sohm Al, all three bosses have several charging modes where they don't even strike the tank for long periods of time. During these bosses I pile on threat, switch to Deliverance, and dish out serious ouchies on the bosses. It's fun to watch a boss get crushed by three massive ethereal saw blades!