Maybe people should take into account that Knuth is a mathematician and computer scientist, not a software engineer. His constraint is correctness under all ci

Maybe people should take into account that Knuth is a mathematician and computer scientist, not a software engineer. His constraint is correctness under all circumstances, an engineering constraint is about efficiency which constrains correctness to a subset of the potential uses. So from his perspective, the problem was something to be solved, not something to be implemented. As such, describing the problem and the solution is much more a literate requirement, being clear about it to the reader, than a computing requirement, being clear to the computer. Personally, I think most software "engineering" is a crock, built on false assumptions and invalid data, subject to fads like "Agile" (or CMMI or SPICE or RUP or...). The software industry would be better focussed on architecture, not the naive patterns of the GoF, but on fundamentals like types and data flows, Nouns vs Verbs and taking the science and making it practical for use in day to day development by incorporation into the tools used.