The issue with a 'realistic' graphical style is that it very quickly expires as technology improves. A good artistic design always triumphs over graphical power. Look at a game like RIFT that blew WoW out of the water, graphically, when it first came out. Compare the two of them now. The fact of the matter simply is that realistic graphics age much faster, and that is a bad thing.That is the only reason World of Warcraft has been able to continue to look decent, despite being run off of an engine that is at least 11 years old.
If they ever completely overhaul the engine and art assets for a WoW 2, I hope they keep the same artistic direction.