Thus future proofing isn't just a waste of time, it's actively counter productive. The predicted requirements are rarely correct although the extra code remains a liability.
Right. And this applies to other disciplines too. "Heavy retrospective refactoring" is exactly what a writer does each time they go back and make edits to a piece. Connections between elements such as characters, themes, writing style, and dialogue are felt out only by emitting draft after draft.
Even this comment went through many edits to get into this shape. These two sentences alone have been rewritten ten times.
In my experience there's also value in imposing a framework once one has done enough emitting of raw material. For code this might be looking for ways to extract common logic out of several similar functions. For writing this might be considering how two characters have "interacted" so far and what other details ought to fill out their relationship (without considering whether or not all those details will manifest overtly in the work.)