When You Are Drawing Art Assets
the easy part is getting the basic shape of the objects down on paper (or screen :))and the more difficult part is getting the material surface of those shapes to appear realistic.
If you are using a laser to render a map of a surface of a real object, most of the work it is doing is the same thing that an artist would do in a few minutes. The subsurface levels a laser could fine tune are less important than the fidelity of the entire shape.
Also, the majority of what you would want a normal map to capture is in the shape that you created whereas the material surface you add to it creates visual noise and this produces a less precise height map.
http://www.katsbits.com/htm/tutorials/creating_bumpmaps_from_images.htm