There are several things I disagree with here, but I'll try and keep the response to just one so that you can continue to expose your views with minimal argument
Quote: Well, how about this scenario which I hinted at earlier, you may see it walk into the room but not spot you. It faces away from you, walking around the room allowing you to sneak to other half walls and hide, passing through a few various side passages before getting to the door... etc
I appreciate what you are saying here. A more dynamic approach to any encounter tends to be favourable, but there is an essential trade off happening in Amnesia for the sake of fear. It is critical to the experience Amnesia is trying to give that you feel utterly powerless - this is most obvious in the lack of any ability to fight, which is great. However, being able to stealth your way around 'enemies' is a form of empowerment - it means you have a way to beat them, to be better than them, it means you are smarter than they are, which undermines the principal behind feeling powerless as a means of creating fear.
It also means the players attention will be drawn to figuring out how to 'beat' them in any given encounter - they'll be analysing the tactical space for shadows, areas to hide, places they can sneak past, and they'll be trying to figure out what the path is, where the 'enemy' is stopping/waiting/looking etc.
You want the player to consider the monster to be unknowable, intelligent, unbeatable, infallable. Considering the immense challenge and comparably small payoff for actually implementing a dynamic AI that is capable of such feats (which would be increadible, don't get me wrong), the best way to achieve this in a game like Amnesia that is not set up for multiple play-throughs, and is trying to achieve this particular sense of fear from it's monsters, is scripted events.
First time I was playing Amnesia, I felt like I was being hunted by something intelligent, and that was what made it completely terrifying to the point where I didn't want to continue, because I knew all the horrible things that would inevitably be done to me if I were to continue. If I had a way to 'win', and knew that the game would not throw me into totally unfair situations, I would have been looking for how to win instead of purely immersing myself in it's rich world, and probably would have finished the F-ing game
The interesting thing to note about the design of the gameplay in Thief, and to a lesser extent Deus Ex, is that you feel powerful when you are hidden, and weak when you are exposed. If you are a good player, then you
can not be seen, and therefore stay powerful.
In Amnesia, you are not focusing on how to play the game well, because there is no way to play it well - no matter what you do, this 'enemy' *will* find you, it *will* chase you and there is nothing you can do about it, and as a result you never feel powerful, and you instead turn your attention to the details in the audio/visual representations that build such an increadible atmosphere, and in turn draw you that much further into its world.