The giant reason to do this with the headset in particular is that getting it wrong means a literally painful and/or nauseous experience. Meta is willing to let that happen with its $300 headsets mostly bought as gifts for children, but the bar is a lot higher for a $3500 device and Apple is already acutely aware of the blowback from "you're holding it wrong"-type scenarios.
I think this is a valid reason, and hopefully the driving factor.
On the other hand, Apple certainly seems to bank on making their devices as exclusive an experience as possible. They sell a huge amount, but they want the customer to feel like they are part of an elite group. This will heighten the artificial sense of scarcity.
> Apple is already acutely aware of the blowback from "you're holding it wrong"-type scenarios.
And the funny thing about what the legions of Apple faithful who were willing to pretzel themselves into contortions defending that.
(For a more reason, mention Batterygate and watch them come out and tell you how you just don't understand, Apple was absolutely doing you a favor, somehow.)
(Just like when they quoted me $900 to fix faulty charging on a MacBook, device worked perfectly, battery was healthy, just could not be charged. "Perhaps we should talk about getting you into a new Mac instead...?")