I just spent some money on more books about the Saxons, who lived in England and ruled it prior to the Norman conquest of 1066. I am working on a part of the book where I talk about the Saxons. I had to ask myself this question before I clicked on the purchase button: Why should we care about the Saxons?
We care about all this old stuff simply to show how deeply rooted our culture is, and the institutions that have grown up on that basis. This means that very basic changes in how we do things, what we want, what our aspirations and life-plans and life-goals are going to be, are simply not going to happen. As a result, we have certain strong points as a culture and we should be playing to those strong points. So it is not a matter of establishing whether people actually thought that much about the Magna Carta in the centuries before Lord Coke, or whether we have unimpeachable evidence that the Saxons lived in single family homes (though in both cases I believe the answer is yes). The point is the continuity over the centuries, with changes being bounded by these basic Anglospheric impulses. The point is not antiquarianism, as much as your authors are in fact antiquarians, but to show the incredible depth of this continuity.
The further point is that America 2.0 was a partial detour away from some of these things, with a constant pushback by ordinary people who wanted autonomy, their own homes, their own businesses, middle class respectability, mobility, etc.
And the yet further point is that America 3.0 is shaping up to even further get us back onto the track we have been on for all these centuries, while taking best advantage of all the new technology which is coming along. Your authors want to encourage and facilitate that because it is the most natural fit with the deepest roots of American culture, and thus the most realistic path to the continued success of the American experiment.