while also preserving spacial cues around instruments that make instruments sound denser, rounder, larger and more organic in space
That would be retrieving ambient detail on the recording - a good system will retrieve it and it will not be masked by distortion from the energy of the pprimary sounds (high S/N, low distortion and great dynamic range necessary to get the ambient stuff). This means you hear the "room" around the artists or the "virtual room" that the recording engineer created (through added reverb in teh mix stage and through real effects like voice plates, mike distance to floor, or a concert hall in the case of a live recording etc.)
If you have ever had the odd impression someone moved up to stand close behind you (you did not see them) but were rewarded when you turn around... that is ambient sound - just a person standing in the doorway may be enough to clue your brain that someone is there. We use it all the time. Some people feel sick in an anechoic chamber due to the lack of spatial cues. Without it a recording sounds terrible and anemic.