I was ranting recently about some stupid UI design decisions in a certain piece of CAD software.

There is, of course, no requirement that sophisticated, powerful tools be hard to figure out and use. A case in point is McNeel's Rhinoceros 3D, a popular CAD / modelling program based on NURBS mathematics.

Part of the beauty of this program is that it does not force you to use any particular user interface paradigm. Almost every command you can think of has a menu item, a toolbar button, and a command-line syntax.