What are the benefits of using computer aided design?

CAD allows for testing designs and ideas before you build them. For example, I am in a robotics club within my school, and we always draw pieces of the robot in CAD before we start building. By doing this we can see whether any of the parts will conflict, where excess stress is placed on the machine, and others, depending on the program used. I like to use Autodesk Inventor Pro, but I have also played around with SolidWorks and PTC Creo