The underlying principle behind teaching (except for higher eduction) is not to make productive workers but knowledgeable and discerning citizens.

The number of programmers we need is not relevant here: they may not need to know how to write complex programs, but knowing the basic principles of programming will make them more able in a worlds relying heavily on computers. This is already the reason why we teach basic math, physics, biology, history, geography, English, etc. to kids.