Colored wireframes are immensly useful when objects are surrounded by other objects.
If you are in wireframe mode and have a lot of objects packed tightly together you can not differentiate the objects at all because they are all black. In many cases switching to solid view does not work because the desired part is sourounded by other objects.
Or you switch to solid view hide the surrounding parts and then unhide them again. this takes very long, esspecially because you probably have to look for that specific part multiple times while working on a scene.
Imagine a car enginge. It consists of thousands of objects which are all packed tightly together to make them fit into the front of a car. If you are looking for the piston rod then you can not simply turn on solid mode and click on the piston rod because the piston rod is somewhere inside the motor.
You can also not use the outliner to select it because objects in imported CAD data usually have names not deciphrable by humans. Parts usually have names like: A109__9DF__179_b.
Now, with colored wireframes you only have to open up the whole thing once, note that the piston rod is yellow or give it some sort of color you can later identify it by and there you go. You will never have to unhide anything anymore if you want to find the piston rod. Simply click on the yello wire and there you go.
Looking for all screws in the motor? Great, because in the beginning when you got the data you made them all green.
Got a terrain with a gazillion trees on it and want to distinguish things from the orthogonal front view because you have to organize the piping underground? No problem, the terrain is brown, the trees are green and the piping is blue. Now, if everything is black you are back to hiding everything.
But hiding the terrain you want to lay pipes in is bad because then you dont see where you are putting the pipes. And hiding the trees is also bad because if you can´t see the trees you don´t know where you can go up and put a hydrant. Or you can but you might notice later that you put your hydrant right inside a tree.
In Archviz it is usefull because in Archviz you allmost allways have stuff inside a house. So if you want to select a chair you can either open up the roof, move inside in perspective view (which makes it impossible to preciely place your chair) or you can simply click on the blue wires because you know that chairs are blue.