I am sure if anyone remembers the game Thief, they'll remember these features. I always felt these were the two things missing from Oblivion for a sneaky character.
Thief didn't let you press against walls, it wasn't added until Thief 3
Being able to affect lighting would be neat but that has a domino effect on stealth features: enemies need to react to this, which means enemies need better anti-stealth AI in general, and then combat and magic need to be just as involved, etc.