What no one outside of Apple knows, however, is why they may have done this.
You're absolutely correct. However, we can still speculate
Mainstream publications and prominent YouTubers typically review products within the first week or two of their release, then move on to the next new, shiny thing. Very few ever update their reviews of "old" products. So, potential APP buyers looking for reviews now will find those initial reviews and figure that's the product they'll be getting out of the box.
My theory is that Apple reduced the efficacy of ANC in response to complaints that the stronger ANC was causing headaches or making users queasy. That's bad press that won't go away unless it's fixed. And since the APP had already won rave reviews in the technology press about how great the ANC was, it became easier for Apple to tweak ANC after the fact.
Fortunately, some high-profile publications (Forbes, Macworld) and websites (RTINGS, Engadget, The Verge, Reddit, and Macrumors) have brought the ANC issue to light. It will be difficult for Apple not to address this, either "silently" with a firmware update that gives us great ANC again, or with a public statement that explains why they won't or can't.
There's another possible outcome, though, that concerns me, which is Apple might claim ANC under 2B588 is the same it was at launch, and that will be the level of ANC moving forward. Unfortunately, the RTINGS assertion that ANC under 2B588 was virtually unchanged from the launch firmware has given those who tell us that we're just "imagining things" some ammunition.
