[ellimilial]

There certainly is quite a lot to be said about constant requirements drift. However, this is not something untypical to some of fast-paced product work or, even more closely, r&d effort within the industry.

What then drives the improvement of the code quality is the potential need for continuity and knowledge retention - either in the form of iterative cleaning of the debt or the re-write. This is reliant on the perceived value for the organisation. From this perspective it's more straightforward to get to author's reasons.