I have to strongly disagree with you on that assumption with WoW.
What killed WoW was how the developers built content and failed each expansion in what they really wanted, a polished game.
Rift has some tweaks but overall, the opening was very polished compared to Vanilla WoW + every expansion after that.
Also, when the developers listened to the players, the content in WotLK was more focus towards Casuals than Hardcore fans. WotLK also focused on balance over content which made PvP better. Cataclysm was just horrible under the current developers. They say this and they do that is the motto I got from that expansion. The developers refuse to listen to well constructed posts on their forums, they made so many restrictions on the forums that you cant even post a negative topic about how the developers screwed up because they just delete them.
But if you really want to know what killed WoW: The community.
WoW was fun in BC & yes there was a lot of QQ in WotLK, but the problem is the developers need to listen to the majority of the player base. When a company asks you to leave feed back on how to make their product better, they actually want to know. Blizzard has stopped doing that. The community cant as a whole produce proper or constructed feed back because they cant say negative things about their game.
You know what is the worst, the old forums had an off topic section, the new forums don't. You know why? They don't want their player base to read stuff on their forums about other games like Rift or SW or GW2.
These are all just my opinion about how Blizzard has failed (ME) as a customer. I liked Trion when they pushed out hot fixes like they do and patches because its better business. Also, I think Rift has a better community which is allowing feed back to go to the developers.
If you ignore feed back from your customers, your going to end up like blizzard, losing 100,000 subs a month. When these other MMO's come out, I wouldn't be surprised if that loss of subs goes to 500,000 or higher.
Edited, Jul 21st 2011 8:21pm by Thalais