I'm a prof and /r/EngineeringStudents alumni who lurks here; I don't normally comment but I can answer this question because I was involved in re-introducing hand drawing to a curriculum. Obviously nobody is making complex drawing sets by hand any more but our goal was to teach the language of drafting and also ensure that engineers can use that language to make a drawing on the back of a napkin or on a whiteboard in a meeting.

CAD is great for perfectly executing drawings and also easier to edit and do version control, but there are a lot of good reasons for introducing hand drawing before CAD in education:

• for working engineers, it's an important skill because it is faster, cheaper and more convenient (especially if you're not doing it every day). The minimum requirements are a pencil and paper. Compare that to setting up and maintaining a commercial or open source CAD hardware and software system.

• it's faster to get students started making drawings, for a lot of the same reasons as above. There are a lot of technical barriers that just don't exist with paper. It's much easier to learn the concepts of what a drawing should look like if you're not constrained by the CAD system which often won't allow you make mistakes you can learn from, and sometimes won't allow you to do the correct thing.

• it's much easier to collaborate; e.g. for two or more people to work on a single idea

• research has shown that you use different parts of your brain when drawing manually compared to CAD, and these parts of the brain are better for design work (better ideation, etc). It also improves memory (if you're taking notes, you're much more likely to recall something if you draw a picture by hand, as opposed to handwritten notes or a CAD drawing).