@AureliusSir: I think that's a pretty big blanket statement you're casting over the idea. Not every enemy needs an AI set to the highest difficulty-- these things have to be tuned reasonably. And probably for many early and low level encounters, it would be sufficiently enriching just to have randomized and/or unique scripts. But for bosses and higher level play, AI is definitely not an automatic slap in the face to your average player.
Server strain is easily the most valid concern about the use of AI, and I would hope that it would be weighed accordingly.
There's only so much you can do with AI, especially in an MMO. There's nothing wrong with mobs that respond to a particular situation with a particular kind of attack or defense, or mobs that move during an encounter for a particular reason but at the end of the day the scope of the AI has to be balanced around the tools players are given to counter it. If at any point an encounter (excluding large group end-game affairs) is deemed impossible without a particular class or a particular skill being available, it's broken. I'm hoping that SE has learned from their experience and the experience of other MMO developers when it comes to realizing that idealism has little/no place in MMOs. How the developers want
things to work has to be balanced carefully around how experience has shown them is likely to be the reality.
It's about balance and smart design, not the flights of fancy of bored hopefuls. No matter how good the idea sounds or how interesting it might seem to be, at the end of the day it has to find its way into the game mechanics in a way that preserves the interest without sacrificing playability.