As something for beginners, this would be great. When you start learning a new skill, it's important to have that feeling of tangible achievement to keep students motivated. Anyone interested enough to pursue a career in game dev will dig into pyglet to understand what's happening, as they start to push the limits of the knowledge gained from this kind of exercise.

And then here's the other nice lesson: students can learn that they don't need to know everything before they start making cool and useful stuff. The confidence that comes from knowing that is just as important (more so?) as being able to implement pyglet from scratch if necessary. The former is a skill used daily, whereas the latter -- well, consider how often in your engineering career you casually rely on the work of others to power your creation. Has anyone ever required you to write a WSGI implementation, or a framework?

That's been my experience, at least.