What's the problem, you're probably thinking, or maybe you're thinking about pennies and kittens, I'm no mind reader. Plus, I'm writing this before you get a chance to read it, so while I'm composing it you're not even thinking about what I'm typing because you won't read it until later and I'm also incapable of prognosticating the future.
Anyway, the meat of the issue is that "causing weapon damage from both melee weapons" phrase. It's why every serious DPS fury warrior has the Glyph of Whirlwind. It's why fury warrior DPS drops when they're in the middle of a Freya or Vezax trash pull and they actually watch their bloody attacks and don't just blithely break CC by spamming the Whirlwind/Cleave buttons like a deranged monkey. It's why they're good to help kill Snobalds on Northrend Beasts and bad on Faction Champions (because Faction Champs take a lot less DPS from AoE) because, frankly, Whirlwind isn't treated like AoE by fury warriors.
Whirlwind is in fact hit every 8 glyphed seconds by every fury warrior. It's used on every boss. It's used on every pull unless specifically told not to use it for CC reasons. The core of the current TG fury warrior rotation is 2 Bloodthirsts and a Whirlwind, with an instant Slam if it procs and a Heroic Strike to bleed off rage or if everything's on cooldown and you need a button to hit. This supposed AoE is not only crippled as AoE (really now, 4 targets in the age of Fan of Knives and unlimited Thunder Clap?) but it's basically never really used as AoE anyway, it's a straight up second instant attack to be used in tandem with Bloodthirst. But Bloodthirst is a pure Attack Power based ability. The weapons you're using really only matter for BT in so far as they contribute rage to use it via increased white damage, and attack power via stats. Whirlwind, on the other hand, is directly improved by weapon damage and it also factors in the increased damage from having two big two handers equipped.
In short, Whirlwind is bad AoE but amazing single target DPS (or, to be fair, amazing up-to-four-target DPS, but that's not something we hear lauded very often) and has become the backbone of fury DPS ever since it was changed to hit with both weapons back in patch 2.3 but what made Whirlwind good in BC makes it too good in Wrath. It wouldn't be so bad if it were merely a weapon damage strike (Cleave is based on weapon damage, as is Slam and fury warriors cast Slam instantly) but the combination of its instant cast nature and the fact that it is the only ability at the disposal of a fury warrior wielding 2 2h weapons that hits with both weapons at once is what makes it a perfect storm here.
By itself, the increased attack power and white damage of a TG fury warrior is balanced out: neither Bloodsurge cast Slams nor Cleaves nor even Heroic Strikes take advantage of the high DPS of the offhand weapon. Fury warrior AP is inherently higher than other melee DPS hybrids but they have damage that bypasses armor entirely or rely more on bleeds or other forms of damage. The higher AP of fury warriors is balanced out by doing purely physical damage on most targets, damage that is mitigated by armor, and reliance on Deep Wounds was modified to keep it in line with this strategy. But by allowing Whirlwind to hit instantly with two big two handers, it becomes a necessary part of a fury warrior's rotation and the only one that really takes advantage of the DPS and top end damage of that offhand weapon. There's a reason the Jawbone was so popular with fury warriors in Naxxramas.
In the end, what I'd like to see is absolutely unlikely to happen. What I'd like is to see Titan's Grip un-nerfed and Whirlwind either converted to an attack power based attack or Whirlwind made a proper form of group AoE damage with no target limit (mobs within the range get hit, period) and a range increase to 10 yards. In return, the cooldown would be increased so that it's not usable as a second instant in rotation with Bloodthirst anymore, and a second attack would be used instead. A fury talent or glyph that made Victory Rush usable every eight seconds or so would allow it to fill the role Whirlwind does now as an instant cast DPS ability to weave into rotation with Bloodthirst, and it's also based on AP so you wouldn't have to worry about weapon damage from two huge beasts. Allow for higher white damage to make rage generation smoother, it's all physical so it's mitigated by armor but doesn't get the double whammy of that second 2h, and if people are bound and determined to get that damage out of Whirlwind every 20 seconds or so (however long the cooldown would be) it would not only not break anything at that point but they'd end up kicking themselves if an actual AoE situation came up and they didn't have it.
There. Now that I'm done dreaming, I'm going to go get that pony and ride it to the Newport Creamery so I can eat an Awful Awful. I miss Awful Awfuls. I probably couldn't handle three like I did when I was a child, but time makes fools of us all.