One thing that makes DB currently visually jarring is the lack of grime in the corners of, well, everywhere. This is not just to beautify maps but to give players better visual cues about the map geometry. Darkening the corners and adding more weathering effects (especially in sooth-covered old London) would help a lot.
I wouldn’t dare asking this in an Idtech game but UnrealEd has a really convenient texture tool which shouldn’t be too demanding on the environment team.
