I agree with your points about distraction, and I think "Deep Work" is a critically important book. That said, it's easier said than done.
I only have one iPad and I do use it for many things including work, and it is shared with family members. That makes it full of distractions.
I have thought about getting a second iPad dedicated to reading, but since you can't uninstall Safari, I feel I'm going to end up getting distracted by the Internet. I'm not confident I have the self-discipline to never go on the Internet when it's just a tap away.
I do think having an iPad-like device with no functions except a book reader would be an interesting product.