EQ and WoW"s conditioning models were totally different.
EQ"s success and resistance to extinction (as evident in the 100000 nostalgia threads) is that it"s condition system was like this:
Rewards: Random and infrequent.
Punishments: Severe and frequent
This is a fantastic model for psychological conditioning. Random, infrequent rewarding is the strongest method of conditioning and has the highest resistance to extinction. This way, when the curve of rewards got smaller and smaller the longer you waited for the reward, your resistance to quitting was quite strong, you were willing to put up with TONS of waiting and pain in the ass situations to get your reward. How many times did I camp seb for the Undead bard to get the Singing Short Sword only to have Triton swoop down and destroy Trakkanon before my guild could even get 20 people there? But I kept going back and sitting there using my Siningsteel Helmet to try and glitch the Eye of Zomm down into Traks lair to spot that Bard!
This isn"t my opinion on conditioning, it"s got a huge body of psychological research behind it.
Now, WoW"s conditioning model is alot different.
Rewards: Semi-Consistent and semi-predictable.
Punishments: Near non-existant.
This is a totally different model for conditioning. It is a much faster and immediate reward, so much so that players are conditioned to be averse to a delay of gratification or random, infrequent rewards. The average wow player would never, ever suffer through EQ style waiting and punishment/reward, but not because they can"t, it"s because WoW has spent the last 5 years conditioning them in a totally different manner.
EQ, the promise in the conditioning was "It"s going to take a damn long time, and really piss you off, and really test your patience and ability to play. But when the reward does arrive, it"s going to be so great that all the effort will be worth it." The human brain get"s addicted to this style of conditioning and will resist the "losing interest" impulse for a very long time. People would play and literally do nothing but farm AA"s in the same camp spot for day and days, just for the chance to race another guild for the Boss that spawned every 3 days, and even then, you may not get the boss, and if you do, the loot was sparse and rare. But by god, your first Yelinak kill when racing another guild, that was stuff of legend. And if YOU actually got Yelinaks head? That just bought Sony another year of your business, no questions asked.
WoW, the promise in the conditioning is "It"s going to be pretty easy and predictable, but we"ll reward you every day, sometimes every few hours. It"s not going to be some epic achievement, but you"ll have something small to reward you every single day."
This conditioning method has a much weaker resistance to extinction. It"s like a clock. As soon as those hand stops moving, you know it"s broke and throw it away or replace the battery. How many people quit until Ulduar came out, since the rewards were just got? Got all their Valor badge loot, their KT and Maly loot... now what? There"s no rewards, and no need for any patience or commitment since you know nothing is coming. You can map out your EXACT path for Heroism/Valor/Conquest badge loot, your exact time commitment for farming Honor and getting PvP gear, check your map for herb or mining nodes, everything. As soon as there is a pause or a drought in reward, interest immediately dies off.
There"s a reason why EQ is nostalgic and seems like the "golden age" and WoW does not. It has very little to do with the "content" and everything to do with how the game doled out said content and how each company chose to condition the human brain.