I dont really agree with you regarding the performance of the various modes. The engine scales fine dependent on the workload you give it and the various shader settings you set. That is also completely dependent upon the area being rendered as well. I havent had any massive problems tweaking this game. You just need to figure out your CPU/GPU bottlenecks. As the game is limited dependent completely on the area you're at. I dont know what computer system you own. Both my computers I've been able to get acceptable performance/IQ out of. But the sky was never my aim for either setup. I had some fairly realistic expectations for EQ 2 performance.
WOW's graphics engine is nothing special, it's just a hacked Warcraft 3 mod, what the developers and artist did with it, however is quite special imo. Imagine what they could do with Unreal engine
WoW artwork IMO is not as special as you make it sound to be. Its based upon warcraft 3 artwork. And it fits the Warcraft 3 universe. But it's nothing thats been radically changed from any previous Warcraft game. It's meant to be a cartoony MMORPG. And there is nothing wrong with that.