How do you know you didn't take any courses not related to your degree? I find this very surprising coming from someone in AI, as it's a very interdisciplinary field, borrowing from statistics, optimization, logic, neuroscience, psychology, control theory, language, etc.. Look at your own field and the failure of expert systems. For a long time, statistics was not core to AI research. Now, some of the most successful AI techniques in robotics have a foundation in statistics. Or consider reinforcement learning, which has roots in animal psychology. As an artificial intelligence researcher in the 80s, you might have looked at animal psychology and said "Bah! I don't want to learn that! It's not a core degree requirement! When would I ever need that?" Because of the interdisciplinary work of researchers in the 80s, animal psychology in the form of reinforcement learning is now a core component of your field.
I think the bottom line is you just don't know where you'll find inspiration. Maybe you've missed out on a lot yourself, and I don't think that's something to be proud of.