IMHO, little that you mention, the books, the open source projects, the magnitudes of complexity, the math, code-kata, the introspection, whatever, has much to do with what people need to develop software. What you need to be able to do is take crazy shit thought up by management, clients, contractors, government, and turn it into good enough software. The job is to appease those who are paying and attempt to squeeze as much good code into it as they can tolerate.

Get passable at that and someone will give you a job.