The best AI design principle includes two parts:

First, how to kill or how to end your enemy

What's the difference between next-gen and FC? Every one can say: oh, beautiful graphic!! Maybe the Japanese RPG fans will say: oh, cinematic CG and fantastic huge world. But only a few people can sense there is a revolution in the AI design part. We can take the God of war and Gears of war as example. The abuse killing and technical finish attack is the core highlight in god of war, you laniate the small monster or rip into their month with blood spray out. All the details can be presented in the next-gen. and all the details is what next-gen can do but FC can not do, It makes our game more exciting and even humorous when you kill your enemy. To exactly speak, the next-gen offer game developer more visual and lifelike animation to present how strong our character is and how misery our enemy is.

Second, how to make use of your enemy or how to fool your enemy

This principle is eternal because it needn't count on the function of all platforms, it don't need the best graphic card and HDTV, it totally base on the human nature--- intelligent interactivity with everything. Nintendo is much clever than the other developer because Nintendo can use this principle to create a worldwide famous game named Super Mario. Of course there are many elements to cause this game succeed, such as collection, hidden playability, funny animation, but the main principle for AI design is the best part. Almost every enemy (including the static actor) can be fooled or be used by Mario, this is the essential difference between Mario and other action game at the FC epoch.

Conclusion

The two principles are all based on human nature. The first one is based on our instinct to destroy with violence, even kill your enemy by a funny way. The second part is also based on our instinct-to use or be kidding your enemy. So, if a game can combine the two eternal principles together such as God of war and Gears of war, it must succeed. I can offer two examples as reference.

First, berserker level as the first Boss in Gears of war

You have to make use of the berserker to break the door, then you can get out to the square to find hammer of dawn.

Second, a puzzle level in God of war I

In the room there is a monster, only when the monster walker on the platform, you can use your skill to stone it, the door can open for seconds, and then you must roll fast to get out that room. You can recover your magic illimitably.

So I think if we want to make a good game, simple killing will not be acceptable.