In my game the Legion commander is facing a bookshelf, with his back to most of the room. I can turn on sneak (with no points in the skill) and take every single item from his room (even the books on the shelves in front of him) without him noticing.

That just shouldn't be possible. I'm not even sure if it should be possible with a large point investment in sneaking. Even if people don't notice you, they should notice items vanishing right in front of their eyes.