A number of programmers prefer writing programs they do understand, and still these programs can do incredibly interesting and useful thinks: theorem proving or

A number of programmers prefer writing programs they do understand, and still these programs can do incredibly interesting and useful thinks: theorem proving or verification, finding optimal solutions to all kind of problems, ... AI as it is now is merely brute force: huge datasets, huge computers. Of course it yields results: that would be a shame it would not using so many resource.