Seem's blizzard have actually thought about this,
First, we’ve been looking at the prevalence of Barbarians in group play beyond Greater Rift 80 and how they’re being used. While many classes bring party-based buffs, the damage reduction of Ignore Pain – Mob Rule combined with Pride of Cassius is currently a clear outlier. As a result, we’re reducing the party benefit of Ignore Pain – Mob Rule from 50% to 25%. To ensure this doesn’t harm the overall viability of group play, we’re also reducing the damage of monsters at high Greater Rifts. This allows not only groups with Barbarians to remain near the same levels in terms of incoming damage, but it affords alternative group compositions greater survivability.