'Proper', 'dynamic' shadows and lighting. 'Dynamic' objects, e.g. moving hair.
It can do it, just not well. The shadows are really dynamic, but the periodic shifting for the sun direction was not the best decision.
It doesn't let you see out the windows of your house unless you want rain through the ceiling. Very 1994.
The rain through objects was sad indeed. I was so excited because I thought I read that it wouldn't happen.
More than 20 NPCs on screen :/
Ive had more. Your computer must not be powerful enough to handle the load of more then 20. But considering each NPC has unique AI packages, unlike the mob AI most games use, having 20 on screen is a major accomplishment.
Having a completely open world without any load screens. One day...
The engine can do this already, they just don't do it for performance reasons. Having all the NPCs from cities processing in the main world would kill most computers. Dungeons are put in their own cell to allow control over the atmosphere as well as allow better cluttering, If they were in the main world, they would have to cut down on the small fun details for performance reasons.
Apparently the ability to show your character opening a door, pulling a lever or getting into bed.
It can do this as well. There are mods for oblivion and fallout to show your character getting into beds. Its just a matter of adding a script to every door telling the player to play the animation before activating the object. Its not very different then the animations used for the crafting skills like forges and alchemy benches.