Why is eyebeam the thing that makes DH's good at clearing visions? It's Blade Dance/Death Sweep that most of the AE damage comes from with Trail of Ruin, plus the movement speed. Eyebeam only looks like it does a lot of AE damage, it's really not that impressive in damage. You really only hit it because it procs FURIOUS GAZE for 12 seconds and TURNS YOU INTO A BIG FUCKING DEMON for 8 seconds.
Also I think you're significantly under-rating ret pallies, warriors and DKs. Well-geared fury warriors are on par with DHs and DKs aren't far behind, just need some movement speed buffs like the 20% run speed food because DKs are the most fucking wheelchair class ever. That Unique-Equipped 5% run speed gem that nobody uses is also way better than +50 to a secondary stat gem for most classes.
Also, class abilities don't matter once you can stack 4 ranks of Twilight Dev. A tank with 4 ranks of Twilight Dev will probably solo clear it faster than anyone because the mobs will only have half health while their twilight dev will do double the damage of a DPS class due to it being 24% of their massive hitpoint pool.