The people with iPhones are still Apple's customers, and it's their messages that are disappearing. That's a perfectly good case for a CAL.
Suppose that someone tried texting someone for medical assistance (silly, I know...), and that message was not delivered because the recipient changed their phone but kept their number, is that the fault of the person that changed their phone or is it the fault of Apple for not being able to realise that people might someday want to change devices?
>not being able to realise that people might someday want to change devices?
They did realize it. There are two mechanisms for handling this issue - turning off iMessage in Settings before deactivating your iPhone, and calling Apple after deactivating your iPhone. Both are documented.
There is no way for your iPhone to know it's been deactivated and still communicate with Apple. If anything it's the fault of the carriers for not providing Apple with an API hook for "this iPhone was just deactivated."
Also SMS is many times more lossy than iMessage. I've had messages show up to my friends on AT&T several days after they were sent, and not all. SMS messages longer than the length limit almost always arrive out of order, and sometimes parts don't arrive at all. Relying on non-iMessage texting for medical assistance is stupid to begin with.
The problem is that there are so many edge cases with this. iMessage is a group messaging platform. Replacing SMS is just a small part of what it covers. You might be switching away from you iPhone but you still want to be able to use it on your iPad or Mac. It would be much better if Apple introduced a separate SMS application or created / supported iMessage on other platforms.
I wipped my iPhone which required my Apple ID and password (so Apple knows the device was deactivated) and I called technical support to confirm iMessages is deactivated for my account and three weeks later I am still not receiving messages from people with iPhones. The problem isn't that you have to call Apple but that even after calling them they are not able to help!
They are, but they're not the people posting articles like this. Whenever I see someone bring this back up it's always "I went to Android and something happened...".
I think Apple would be much more likely to respond if a bunch of people posted "My friend went to Android and now my iPhone won't text him". Frame it as issues of current customers.
They've let it go this long, so I somewhat doubt they'll make it easier; they probably would have done it by now. Re-framing it might help push it though.
Suppose that someone tried texting someone for medical assistance (silly, I know...), and that message was not delivered because the recipient changed their phone but kept their number, is that the fault of the person that changed their phone or is it the fault of Apple for not being able to realise that people might someday want to change devices?