Well, I figured the point of the game was to be stealthy and stay in the shadows. That takes time. I wanted to relive some of the 'Thief' stealth experience. But yes, what you say is true.
EDIT: Just finished Amnesia. It took me 16 hours to complete. It was a very good game, although a bit intense for my liking at times and the ending was a bit 'meh'. I think it's time Frictional Games did some other type of game. This was quite similar in many ways to Penumbra. The atmosphere was ridiculously scary and the graphics and gameplay were very good but the locations could've been more varied. Also, I felt the story and characters weren't as compelling as Penumbra but I certainly was chilled to the bone. Some of these things flaws are due to budget, I'm sure. Still, thanks for the memories. Or nightmares.