As I've said before, I wasn't all that impressed with the graphics in Age of Conan. Therefore, I was relatively surprised that I really, really like the look of Dreamfall, which is an older adventure game made by Funcom.
Of course, Dreamfall has a number of advantages over Age of Conan. It's a single-player game with few models on screen and smaller locations. It also uses bright colours, and has that vibrant look that I enjoy.
However, I think a bigger factor may be that Dreamfall is an older game, published a couple years ago. My system is fairly new, and so I can crank all the video settings to maximum. In Age of Conan, I can't push the settings all the way up, and have to settle for medium quality.
It begs the question: is 100% of older graphics better than 50% of newer graphics? Maybe one reason I preferred WoW's graphics is that I can run the older graphics at near-maximum, and that provides a better experience than newer graphics at medium.
I had a similar reaction a while ago, when I played Deus Ex: Invisible War. I played it a couple of years after it was published, and on newer hardware. Again, I was able to crank the graphics to maximum, and I thought it was a really good looking game.
Maybe it's harder to get all the different elements of a graphics system working together perfectly at the mushy middle quality. Maybe the contrast between quality of different elements is a factor. I mentioned that I was very impressed with Conan's water. Did the quality of water diminish how I viewed the avatar graphics? Would it have been better if the water quality was intentionally degraded to match the other graphics settings? Would that have provided a better overall experience?
I'm not sure, and I'm not really into computer graphics. I just found the difference in my visual reaction to two Funcom games to be interesting.
 As an aside, Dreamfall and its predecessor The Longest Journey are superb adventure games. I'm still working on Dreamfall, so please don't post any spoilers.