I think that color by layer could become more useful if there were the possibility to have different groups of colors for different uses. For example, to assign different colors to the different type of structures: walls, windows etc (group of colors A). Then have another line of colors assigned to: new walls, demolished walls, permanent walls (group of colors B).
If in a scene I wanted to see a structural view of my building, I would assign Color by layer A. If I wanted to see a scene where demolished and rebuild parts are shown, I would assign Color by layer B and so on.
Now a component or group can have just one color, depending on its layer. if I could have more than one color it would add a new order of visibility. In big projects, with many components, it could simplify the logical organisation of the system and its visualisation.