From what I've seen of the Avadon screenshots, I think the graphics are just about as good as possible for a 2D computer game. Having the game be 3D would just raise the system requirements, making it harder to port to iPad and making it harder to run on netbook, and making it use more battery power for portable computers. After playing WoW for a few months on my laptop, my laptops graphics card wore out. My poor laptop always spun its little fan so hard playing WoW. I tried to keep it elevated to keep her cool. :'(
Anyway, 3D wouldn't add anything meaningful to the game anyway. It would be nice for desktop users, but laptops are way more popular, especially among younger people who are more likely to play in-depth games like this.