Fair points but largely irrelevant. My issue is not with limits of imagination, I can imagine plenty of uses that this device might do, but cannot. Flat earthers and anti evolutionist do not suffer from lack of imagination but from lack of understanding. Quite different and comparing my point to this viewpoint is very insulting and misses the key point I was making.
The issue I have is that the iPad as currently implemented, which includes its software, does not require an M4 but might if Apple have a different destiny for device. I use my iPads a lot, but I have no way to make them do what I would like. And you are correct, the average iPad Pro user is not the average iPad user, but they are severely limited by the current implementation of iPadOS. An M4 will not help until there is a fundamental rethink in the way an iPad works, Pro or not. Try not to be so judgmental please.
This is a bit of a detour but... Yes, failure of imagination is common in anti-evolutionists. You frequently read/hear arguments like "The eye is way too complex to have evolved! I can't imagine it developing through random chance!". True, there is a lack of understanding, usually a willful one (it ignores the selection half of the variation/selection team), but it truly is a failure of imagination as well. (Fun fact: the eye has independently developed over 40 times.) The same disability drives flat-earthers - the ones that aren't publicity-seekers, anyway.
I think this is an apt comparison to statements like "the iPad as currently implemented, which includes its software, does not require an M4". That's true for you, with your use cases. (It's also true for me with my use cases.) But it's not true for everyone, and your inability to recognize that is the failure of imagination.
To be clear, I agree with you (and many others) that the iPad is too hobbled. I would love it to be able to dual-boot. (Perhaps if a jailbreak is found, some enterprising hacker will make that happen.) But it is what it is. And for some people, more CPU/GPU, even in an iPad, is better.