Unfortunately we can't control what other people do; everyone does what they are driven to do / what they find valuable. (We can at most create the environment and incentives that will influence them strongly, if their own intrinsic drives / values aren't pulling them strongly enough in some direction. But what incentives could sway a tenured Stanford professor who already had a Turing award and was certain what his life's work was?)

What Knuth seems to enjoy are ideas, and teaching/exposition. That might explain why his "literate programming" is structured around the metaphor of writing, rather than that of, say, engineering, architecture, or tool-making. In this case, he has written an “essay” around a certain data structure that we may call a hash-packed trie, a small twist (possibly never done before!) on the packed tries that had been described in his student Frank Liang's thesis and used for hyphenation in the TeX program.

This data structure is uniquely suited to this problem of going through a file and counting words. It cannot be obtained by putting together "reusable blocks". (At most it can itself be packaged as a library, but would probably be used only for word-counting, which is the original problem itself.) So I would disagree with your "key takeaway" IMO. What you (and McIlroy) are describing is a different approach where one does not try to arrange for a problem to be solved using the data structures and algorithms best suited for it, but tries to express the problem in terms of existing “blocks” even at some cost of efficiency or other considerations. This is a perfectly fine philosophy on its own (see the quote above about "prefabricated house"), but it's not the full story here.