Many people hate murlocs in World of Warcraft. But when you consider the reasons for it, you'll see that murlocs are hated because they are slightly less dumb than other mobs: many of them use ranged combat, and thus can't be pulled away that easily, and when they are hurt, they run for help. That makes them annoying to kill, but also shows how MMORPGs are designed around artifical stupidity. Even with the most intelligent races of them, a single adventurer can kill half their settlement in plain sight of the other half without anyone noticing or reacting. That is essential for soloable gameplay, but not very bright.
This explains why work on artificial intelligence in games advances so much slower than work on lets say graphics. There are graphics cards, and physics cards, but the "AI card" never took off. Because more graphics power is always good, but too much artificial intelligence is just plain bad. If the first mob in Karazhan would do the logical thing and shout for help, so that all of the mobs in the place come running to repel the intruders, even the world's toughest raid guild wouldn't have beaten the place yet.
One argument for PvP features in MMORPGs is that they would provide players with intelligent and unpredictable opponents. But being intelligent, these opponents object to getting slaughtered, which is why even PvP-centric MMORPGs need dumb PvE monsters, who don't mind getting beaten all the time, and don't log out to roll a new character on the winning side instead.
Artificial stupidity is a design challenge. It isn't actually all that hard to program mobs which would play WoW better than a human, because they have much faster reaction time, and playing WoW well doesn't actually require more brain power than a PC can provide. It is hard to program mobs who *seem* to react intelligently, and still manage to lose all the time. The standard "taunt" and aggro management mechanics are a typical example of artificial stupidity: It's stupid for the mob to hit the best armored and least dangerous member of the player group. But it plays well, because it is just hard enough for bad groups that make aggro management mistakes to fail as a result of it. That gives the players the impression that by good aggro management they outwitted the mob, and winning because you play well is fun. That works so well that nobody has come up with a better method yet. Even Age of Conan, with its superficially different combat system still relies on taunts and aggro management in group combat. If the devs wanted to program better artificial intelligence, the mobs would kill the healer first and the mage next, and MMORPG combat would be a lot different and less fun, especially for the cloth wearers.
So what the future will bring is monsters that are still stupid, and still lose all the time even if they have superior numbers. But maybe somebody will manage to make them appear more intelligent. The one field where MMORPGs could use a large dose of artificial intelligence is with NPCs: Many quest NPCs don't even recognize you any more five minutes after you saved them from death. More intelligent NPCs could act as source of information, giving you directions to quest goals for example, which would be better than looking the quest locations up on Thottbot. But even for MMORPGs game companies spend far more money to develop graphics, than to develop an artificial intelligence that would make the virtual world come alive. Artificial stupidity is here to stay.