One of my the things I really liked in Torment and which I felt set it apart from many RPGs (especially modern ones) was how so much of the game's content was not hidden but not glaringly thrown at your face.
* You could approach a seemingly random NPC, and the conversation would stir up a memory, granting you XP (perhaps some random NPCs recognize your shell, or think they recognize you?)
* Sometimes a very long dialogue would yield nothing (in terms of items\XP), and sometimes certain branching in the conversation would lead a new quest\item. I fondly remember the astral traveler in the burning man pub, which gave you the shadow token. An item you can get at the start of the game which has a great significance later on! (a numenera early one which only proves useful later?)
I think letting players discover hidden gems in the game on their own gives a very strong replayability value, and gives players the illusion of a much richer and non-linear world.
Yes! This makes a tremendous difference!
I think it is already planned for them, they are the same people that worked on PS:T after all but i vote for this just to make sure they know it :)