So what's the secret behind those guilds that have already wiped the floor with Blizzard's current endgame raid content? Is the content's tuning to blame, would they have done it anyway, or do they have special insider knowledge?
Facetious as it may sound, it's all three of these. The sort of guilds that have already cleared everything would have at least tried to do so anyway, regardless of boss encounter knowledge and tuning. It's possible we'd still be seeing TwentyFifth stuck wiping on Patchwerk, had he been ridiculously overtuned -- as it stands, he can cause a lot of pain to mostly-Sunwell geared tanks, but by the time you reach him the sheer amount of loot dropping in Naxx should see your tanks clear with a few upgrades.
The tuning itself is a byproduct of the amount of loot dropping -- while fully Sunwell geared raids do need to make some adjustments to survive in Naxx, upgrades really aren't hard to come by, so by the time you reach Kel'Thuzad your "Sunwell geared" raid... isn't. Having seen the sheer amount of upgrades people have walked away with in just two raid resets, and the corresponding lowering of difficulty of the encounters as DPS, healing and survivability increase, it's not even that surprising that the hardest encounter in the game, Sartharion with 3 drakes up, is entirely doable even now.
This is good news for those guilds planning to enter Naxx in the coming weeks, of course. Even if you only poke at a couple of bosses during your first visit, you'll get some loot that'll make further poking more successful, just like previous raid progression used to be, and if you manage to get a fair few down you'll be showered in purples.
Knowledge of the boss encounters is also a crucial component to defeating them quickly when they go live. Naxxramas itself holds very few surprises to a raid who's already done it at 60, and further practice on beta got people accustomed to the changes that do exist. It's still easy to see, watching someone entirely new to the instance zone in, that there is a lot of challenge contained within its walls -- but for any raid group who put in the time to clear it on beta, doing the same on live isn't a problem strategy-wise. The same goes for Sartharion and Malygos, where novel fight mechanics could have scuppered fast clears, but having done these fights before launch left zero challenge for experienced raiders.
A big question around the fast clearing of content is "why bother?" -- raiders who were waiting for months for new content are now going to be bored again, twiddling their thumbs until the release of Ulduar. Again, a big part of the motivation to clear instances so quickly is to be among the first to do it -- even though this content isn't particularly hard, top raid groups are very proud about their world standing and strive towards high rankings, whether they mean anything or not. People want the flashy "Realm First" titles, they want loot now rather than later, and the raid guild does have to satisfy the hunger of its average member or risk losing them.
Another argument is that there are still challenges to be had in the current raids, with the addition of certain achievements. However, none of these are exactly world news, and while guilds will internally strive to beat the various bonus challenges, we're unlikely to dance in the streets the first time TwentyFifth beats Kel'Thuzad while killing extra abominations. Sartharion with three drakes was labelled the only "hard" encounter, and that's already been defeated by multiple guilds, although the principle is a nice one -- make the boss, in his base state, easily defeatable, but with exponential complexity to satisfy those hungering for something more challenging.
So what are raiders going to do between now and the magic moment when new content arrives? And what will happen when it does?
Achievement and gear farming is probably the primary goal, repeating the more difficult kills and keeping people interested until they literally have no reason to run the content. Then it's time to level up alts and recruit new people, ready for the inevitable roster changes that happen every time a new instance comes out, and to ensure raid banks are stocked with full consumables in preparation for new bosses to wipe on.
How raid progression on Ulduar goes will be very dependent on the PTRs. If the raid content is available for testing, as every recent raid dungeon has been, then if it's tuned for accessibility it'll simply get steamrolled on the PTR and cleared within hours when it goes live. Thus the top end raiders will never be thoroughly satisfied, unless encounters are designed so there is a 'hard mode' similar to Sartharion that they can focus on.
Gated progression, similar to Sunwell, will halt the flow of boss kills but in an unfortunately artificial way, while designing encounters so they take days to beat by top-end raiders has its problems. Players take time off work, ignore their families and alienate their friends while those who don't try to brute force the encounters get stuck on them forever. The advantage of the current level of content tuning is that you can raid and have a social life, or at least a semblance of one.
The days when the cutting edge took weeks, not hours, to defeat seem well behind us, and for most WoW players that's a good thing. By opening up accessibility Blizzard will achieve their goal of ensuring more people see endgame raiding content, instead of designing encounters that only a few guilds will ever beat.
However, the problem seems to be keeping the hardcore raiding guilds interested -- while some might argue there's no real loss if these people give up, they do serve multiple purposes in the WoW community, from affecting the economy and raiding exposure of their own servers to producing boss guides and testing content. It'll be really interesting to see what happens during the release of Ulduar, and whether the hardcore are satisfied.