When people say things like "Well, warriors scale best with gear" or "Warriors are the most gear dependent class" what they are really trying to say is that warriors without gear are just naked girls and guys. Now, this isn't to say that gear doesn't enhance other classes... I'd certainly be happy if I were in Wintergrasp and a mage with no clothes on ran past me, for instance. But said mage could still cast Mirror Image, could still Blink and Ice Block (which I would Shattering Throw on, of course) and so on. A naked mage would certainly be much less effective. A naked, unarmed rogue would not do a lot of damage (like a warrior, they would be unable to use most of their attacks) but they could still stealth and run away. A naked warrior? Well, he or she could still Charge or Intercept to his or her death if that was appealing for some reason.
"Let's get this over with!!" just doesn't sound like a terrifying battle cry to me.
But it's more than just not being able to do things without gear. The way gear makes warriors more effective works differently than for most other classes. Not only does gear allow you to do more damage by increasing your stats (as it does all other classes) and allowing you to use specific melee abilities (as it does for rogues, shamans, paladins and DK's to some extent) but because warriors derive rage from how much damage they can deal and how much damage they can take, gear also multiplies warrior damage potential by increasing both of those factors: the more damage that you can deal with regular or 'white' attacks the more rage you have available to put into your specual attacks like Overpower, Mortal Strike, Bloodthirst, Whirlwind and Devastate (just for example) and likewise, the more damage you can survive the longer you'll stay up to use the rage you gain from taking damage.
This process also works for threat generation although a tanking warrior is generally more focused on survivability and usually doesn't have to worry as much about rage generation since if she or he is doing the job right, there will be plenty of rage coming in through damage taken. Tanking warriors also have the paradox of rage starvation in content they overgear, although it's not as bad now as it was in BC, thanks to higher damage output and strength being a much bigger tool for Shield Block Value. Still, the reason most tanking warriors keep multiple sets of gear tailored for trash, bosses, resistance and so on is due in part to the way the rage mechanic works: if you're tanking a bunch of trash that barely hits you at all or running a heroic in full 25 man hard mode epics, you'll be switching to your threat gear and letting a few more hits land than you would have back when your gear wasn't quite so staggering. Thankfully, the days of warriors tanking pantless are a thing of the past.
Well, okay, for all I know you never wear pants. But I was referring to your character. Myself, I always raid with pants on after an incident with a large glass of icy cold soda and a cat leaping into my lap from the windowsill and my poor, defenseless nether regions. There was dousing and scratching and screaming.
So all of these factors... the way rage interacts with both damage taken and damage dealt, the line between staying up long enough to convert that rage into damage/threat and increasing ones ability to make meaningful use of the rage once it's been generated, the amount of rage you have going up as your various stats (hit and expertise, for example, being stats that you need to have at a specific level to make proper use of the other stats on your gear) make gear and the acquisition of it one that can really be felt by the warrior class in ways other classes simply won't. A DPS increase in a weapon will not just increase a warrior's DPS by that amount, it will also increase her rage generation on every white swing, which will increase the amount of rage she has to use with special attacks which are also dealing more damage since the weapon itself does more damage. The weapon's speed, the weapon's stats, these can all feed into the warrior's constant conversion of white damage into rage into yellow damage.
This process is at the heart of the warrior's unique scaling. Unfortunately it's also the reason why warriors always seem to get beaten about the heads and shoulders every time new gear gets released, and why it's often the DPS warriors who suffer comparatively (although I still hold that Burning Crusade's Rage Normalization was like taking a sledgehammer to a man's testicles just before telling him to run a marathon for you as far as tanking warriors were concerned as well) rather than tanks. Tanks are more dependent on damage coming in for their rage, so if their damage output fluctuates due to changes in talents or by having a few pieces of gear below the curve then it's less immediately damaging for them. (Now if they can't hold threat due to their damage output being too low, that's pretty immediately damaging, but so far Warriors in Wrath haven't had many complaints there.) This leads to a situation where we can often see warrior DPS fluctuate as each new major content push happens, going from competitive places near the top of the charts to struggling to hold on to medium DPS and then, as new gear is acquired, again clawing their way up.
For me this has always had its frustrations. In Wrath, the big issue has been weapons: there simply aren't enough 2h weapons dropping since warrior DPS was moved to a 2h weapon based model. Thankfully as arms you can use polearms in addition to swords, maces and axes, which gives you more flexibility when looking at weapon drops (especially in Ulduar, where there are quite a few tasty polearm drops) - it's still rare to see more than 1 2h weapon drop in a raid (I've gone the past few months without seeing any 2h weapons drop, actually, unless I'm on my shaman) and it makes gearing that particular slot up difficult. It's purely luck oriented. You can craft, run heroics or do Argent Tournament dailies to get a 186 DPS 2h at least which will get you in the door, but for fury you need to constantly keep upgrading 2 slots and you can't even use as many options as arms warriors, paladins or DK's or hunters. Heck, even druids can use polearms now. It's time for Titan's Grip to work with polearms. It's crazy to have a perfect arms weapon drop and not be able to bid on it because I know I won't be able to use it when I switch specs for trash. (I suppose I could bid anyway, but why take it from a ret pally or DK who will use it all the time?)
Other warriors have trouble with other slots: we have a DPS warrior who somehow always manages to disconnect or switch out for someone else just before a ring drops. He's using the badge ring and the heroic expertise ring because he hasn't seen a ring upgrade in raiding from early December to now. Last night, he got stomach flu and had to log off just before we killed Thorim, which meant we all knew I'd be picking up a ring, and so I did.
Meanwhile, an old friend of mine who raids on the same server in another guild is still using the shield out of heroic Caverns of Time because the only shields that ever drop for him are caster shields. (I'm still using it too, because I pass on tank gear unless it's going to get sharded.) It's easy to get superstitious about loot drops when you're a warrior: no amount of people saying 'random loot is random' will ease that nagging voice in the back of your mind telling you that the gear isn't dropping because it knows you're there. I still go back to Naxx hoping that damn Betrayer will drop, and in months and months of killing Kel'Thuzad I've not seen it. It's frustrating because there's nothing you can do: there's no option you can go spend emblems on, there's notthing to be done but wait and hope the upgrade eventually drops in a sea of gear you can't make any use out of at all. (I'm aware that when plate drops over and over again that the vast majority of WoW players just see shards waiting to be DE'd.)
In the end, the gear system will always be maddening and designed to keep you coming back week in, week out once the instances are cleared, hoping for that one last elusive BiS drop. Warriors will always be locked in this cycle of boom or bust, seeing gear that took them weeks or months to farm elevate their abilities and then suddenly their talents will be changed to make them desperately scrabble to wrench new gear from the next instance. It's the nature of the beast. Still, I'd not complain if there were a few more options at the Emblem of Conquest vendor.
Next week, Ulduar Gear.