I take away from it that real programmers do not have an emotional attachment to one or other tool/ language. They are interested to solve a problem with maths and logic and the computer and his language are just the butler; a layer that has to be abstracted away.

Obviously Knuth thinks that books as a medium are still valid. (I am with him on this one.)

I have not read the book nor do I have any clue about Leaper graphs, but for some reason he thought it could help to research this. How can this research / knowledge help? Maybe it's just fun, I don't know.