He strikes me as an old testament prophet telling us "repent in sackcloth and ashes!" He thinks we've been wandering in a desert for 30-some years, and he is here to point out that PARC was holding the map when we got lost.
The thing is that he is not wrong. Computer documents are, for the most part, paper-simulators and that paradigm wastes a computer's potential. You're right that there is disagreement about what we can do to improve things, but he is saying that perhaps if the alternatives weren't fighting the conceptual fast-food that is WYSIWYG, we might have figured it out at some point over the past 30 years.
The thing is that he is not wrong. Computer documents are, for the most part, paper-simulators and that paradigm wastes a computer's potential. You're right that there is disagreement about what we can do to improve things, but he is saying that perhaps if the alternatives weren't fighting the conceptual fast-food that is WYSIWYG, we might have figured it out at some point over the past 30 years.