Now, if we compare the Burning Crusade 2H weapon spread, we see this. The amount of DPS increased between the first and last weapon is roughly half that of the Wrath comparison we did, and even if we take into account that Wrath weapons are of course a much higher iLevel, we're comparing the entirety of BC's gear spread with about half that of Wrath. The difference in DPS between a 2H weapon at the beginning and at the end of BC was about 34 DPS if we use Despair and Apolyon as our goal posts. The difference between a Demise and Cryptmaker is 108 DPS, and Cryptmaker isn't even the most powerful 2H weapon available in non-heroic ICC, that being Glorenzelg. (I'm deliberately not including legendaries in this.) If you count heroic modes then there is a 344 DPS 2H weapon, heroic Glorenzelg, meaning that in one expansion you could see a jump in DPS on a 2h weapon of around 158 DPS. That's more than four times the jump between Despair and Apolyon.
When we consider that each of these weapons also has increased stats and/or potent proc abiliies, we must consider that it's hardly just 2H weapons scaling in this fashion. All weapons, all trinkets, all rings and necklaces, and indeed all armor from cloth to plate has been assiduously ramping up from Heroics and Naxx 10 to ICC 25 hardmodes, to the point where twice new 5 mans have debuted with updated gear at a higher iLevel. What we're looking at isn't just gear inflation. Inflation implies a steady increase, like putting air in a balloon. This is a gear explosion. The trip from iLevel 200 to 277 (almost any player can have at least one iLevel 277 item, the reputation ring from the Ashen Verdict, given enough time) goes through many 'tiers' and dwarfs even the most generous estimation of how gear scaled in BC. Frankly, the difference between Anarchy and Heaven's Fall is greater than that between Spineshatter (a level 60 BWL epic) and the Grip of Mannoroth (a level 70 Sunwell epic.)
Admittedly that doesn't prove a heck of a lot but man, it's wild to consider.
What it does showcase is how minor inequities in game or class design can quickly become exacerbated. A tank in gear appropriate to the heroics that shipped with BC (say, full iLevel 187 blue gear from running non heroics to gear up) has very little chance of holding aggro against DPS who've already geared up to iLevel 232 via the dungeon finder. The recent discussion of tank threat and how it scales less than DPS is fully a consequence of gear increases: it wasn't noticeable at Naxx levels of itemization but going from iLevel 200 epics to iLevel 264 epics, suddenly it's very noticeable.
To a certain degree this makes the idea that we'll be replacing our epics with greens (as folks complained about in BC especially and to a lesser degree at the start of Wrath... a lot of folks I know raided Naxx in Sunwell gear) seem almost ludicrous. It's not hard to imagine even a lackadaisical raider with an Abomination's Knuckles or Ramaladni's Blade of Culling, and I seriously doubt the first green you run into off a Mount Hyjal boar (yes, I said a boar) is going to make you chuck that. Still, we know that itemization is undergoing some pretty solid tectonic shifts in Cataclysm, so who knows? New gear might not have higher DPS but be more in tune with the new itemization schemes.
Since we're only going five levels this time, with (spoilers incoming) rumors of there being four raids to start with, it seems very likely that we'll see more raids that offer less wildly varying gear levels, similar to how ZG and AQ20 offered gear at or slightly above the MC level, while AQ40 offered sidegrades to BWL. Perhaps, too, it's time to consider a system where hard modes drop less gear and more items like mounts and other status symbols that don't have to be itemized, and thus don't have to be more powerful (hard mode gear is the reason for the 'half-tier' effect, where you see Voldrethar at iLevel 239 when non hard mode Ulduar 25 gear is at iLevel 226). Since we know Blizzard likes it when trinkets are hard to acquire, perhaps hard modes could be a place to put some good ones. They wouldn't have to be itemized higher than the rest of the instance, since the paradigm is that good trinkets should be harder to get anyway.
At any rate it's fairly clear that gear levels were a runaway train this expansion: the difference in power between a fresh level 80 in some blues back at the beginning of Wrath (December of 08) and a geared raider today is pretty extreme. Tanks gained more than 30k health, DPS can do three to four times as much damage, healers get so bored that they can heal a run in their DPS specs (and often, their DPS gear) with minimal difficulty. It will be interesting to see how Blizzard reins us in.