WoW is a good linear game. It's got a lot less bugs than most games, and it's well executed and marketed. It's probably the least innovative of all MMOs, but it has taken many other ideas and pulled it off. But to me it's a terribly boring game, as there's no risk. At all. Argueably the first MMO, Ultima Online, was much like a social experiment, as there were no in game restrictions on who you could attack. Additionally, you could steal all their stuff. The result? It was ******* dangerous as these sociopathic geeks were unleashed on each other. This added up to people carrying equipment of good quality, but still affordable, allowing everyone, not only noobs, to PK and survive. Other features such as your own house (and even castle!) was terrific! Ultima didn't have levels either, and it didn't take long to skill up to a survivable level, and as an added bonus, the skill level (0.0 -100.0) didn't make that much of a difference relative to levels in WoW. Oh, and did I mention you could own a boat and hunt for treasure? However, EA happened.
These days you've got Darkfall which is relatively close. All these players have one thing in common - they don't want the safe environment of WoW. Darkfall does have its faults, such as a skill cap which made UO balanced, but as Dagbladet, a Norwegian newspaper, wrote:
"Darkfall isn't the nice auntie that stands at the ready with a plaster and blows on your knee if you've hurt yourself, it's the nasty uncle that chucks you into the freezing water to find out whether you can swim or not."