Well, I was really bored and I had some money sitting in my seldom-used PayPal account, so I renewed my old WoW account to see if I might enjoy bashing stuff for a short while. (Yes, I know, flirting with old addictions is very dangerous, but I lived.)
When I quit WoW I predicted, somewhat bitterly, that Blizzard's various borderline insane decisions (e.g. changing raid caps) would drive people away from the game. I predicted that the server populations would drop by 10% or more. Frankly, with time having passed, I decided my judgment had probably been clouded by ire, and that most of the folks who played WoW would probably deal with the stupidity and soldier on.
Logging back into World of Warcraft -- and I should add that this was just me, just one specific server, and that I logged in during off-peak times on a day when Blizzard had announced rolling outages -- it struck me that:
the usually crowded areas (such as the hub cities Ironforge and Shattrah) were almost deserted
the auction houses had relatively little for sale (and bizarrely skewed distributions of things -- even more bizarre than I remembered)
there wasn't anything on sale in the auction house that represented an upgrade for any of my alts (I have a lot of alts), which is pretty amazing since I quit six months ago before a lot of highish end content had been trivialized
my main (a hunter) was able to upgrade her (very decent, but not uber) bow for 35gp buyout (not a fluke, there were several such bows on sale at roughly the same price)
chat was pretty quiet, even dumb questions in city/general and trade channel spam were minimal
no-one I remembered was online (and I knew a lot of hardcore 24/7ish players)
there is new content (e.g. new factions to work on, new level 70 quests that require a flying mount to complete, etc.) but it's not interesting. Oh wow, now I can fly somewhere, and collect ten doohickeys. That's different.
My brief tour included both the Horde side (where the alt-guild I had been a member of only had three members who had logged in within the past month) and the Alliance, and both "newbie" zones and high end (level 70+) areas.
From what I've heard from friends who, at least as of a few months ago, were still playing WoW, pretty much every uberish guild imploded about the time ours did (i.e. when we'd tooled up 20+ 70th level characters and were ready to hit the "end game"). Coincidence? I think not.
First, Destroy the Social Glue
In order to hit 40-person raid zones, a guild needs an absolute minimum of 60 suitably skilled and geared players. On non-raid nights, this means that you have probably 20-30 raiders online, and on raid nights, this means you have 35-45 on. Blizzard built new high-end content for raids of 10, 15, and 25, but with all the lockout idiocy of 20- and 40- person content. (Anyone with experience dealing with the ZG 20-person raids knows that lockout was really idiotic for ZG, but this wasn't so bad as no-one cared that much about ZG loot except for three bosses, two of which were easy to get to.)
So now you end up with, say, enough people to staff two 10-person raids on an off night. They either sit on their asses, or they start raiding, causing all kinds of lockout issues on raid night. (This was guaranteed.) You had guilds (like ours) fighting over whether they got to go with the (perceived) "A" team, vs. the suboptimal "B" team formed of leftovers, and then everyone went apeshit on raid-night, when there were two incomplete raids with partially locked-out players, and a whole bunch of folks who had a choice of forming raids without the best players (who were locked out) or joining a pre-existing raid and missing out on the easy loot.
And that's just the fallout from one incredibly and obviously dumb decision Blizzard made in the expansion.
Next, Make The Learning Curve Too Easy, and then Too Hard
Other dumb decisions included making the difficulty gradient for the new raid content way too steep. Pretty much all the content (including dungeon instances) in Burning Crusade is idiotically easy, until you hit raid instances and "heroic" difficulty. Then it suddenly gets ridiculously (as in "figure this fight out by dying ten times") difficult. It's the old story of the frog in a pot of water ... apply heat too fast and it jumps out. I guess a lot of people jumped out. It's like Blizzard forgot one of the golden rules of computer game design (learned about ten years into the industry's lifespan): the customer pays to be entertained; he/she doesn't have to do a lot more to deserve that entertainment, and if you treat a customer as if he/she does need to earn the right to be entertained, you lose the customer.
This insight is most clearly displayed by the change in arcade games some time around 1984 so that you could pay to continue. Stick enough coins in the box, you get to see the whole thing. Better players can get away with fewer coins, but they don't get to see more of the game. All MMORPGs have yet to learn this, but they get away with it by deluging players with so much content/tedium that they might not realize they're missing something. The problem for WoW is that the original game set a high bar, and the expansion did not reach it.
No-one at Blizzard with a pocket calculator seems to have done some simple arithmetic, such as "hmm, to get to revered with Enemies of Fred you'll need to kill 234,000 Friends of Fred". Well, the other possibility is that they did, and the spectacular levels of tedium (in terms of factions, keys, and tradeskills) introduced in the Expansion are deliberate.
This isn't surprising. There's plenty of evidence of this lack-of-thinking throughout World of Warcraft, it's just that it has never been piled up in huge, steaming mounds before. It's almost like Sony Online Entertainment was put in charge of Burning Crusade (but then there would be better itemization).
Assuming, and this is a huge assumption, my experiences in my 1h return to WoW were vaguely representative, it seems like Blizzard has lost not 10% of its players, but more like 50%. This is WAY more moribund than I would ever have guessed WoW would become in such a short period. Heck, I'd be shocked if EverQuest servers (merged as they are) would be this dead. That is simply astonishing, and worth a major post-mortem.