It's bad because Apple now has to (OFFICIALLY) support a wider range of devices.
And then there is less incentive for Apple to further improve this interface because any improvements will benefit non-Apple devices (i.e. do the foundational work but everyone else gets the positive exposure)
Apple used to brag that “it just works”. That included peripherals it did not control. Nowadays, it can’t even have its own devices work correctly.
Apple has stopped improving long ago, and it’s not regulation that’s at fault.
Based on the latest iOS / MacOS update they don’t want to improve their interfaces anyway.
You mean it will benefit Apple’s customers, who prefer headphones not made by Apple? If only the incentive for Apple to improve their interface was that its paying customers will have a better interface.