Silhouette lines currently exist where one object is in front of another object without consideration for how far the objects are apart. This means that a piece of trim that is 1" offset from a wall will have the same silhouette line as a building 50' in front of another building.
Silhouette line width should be relative to the distance between the object in front and the object behind. Depth cue is not a replacement for this age old representation of position in elevation and section.