The reason for Hart's low opinion of India become evident from his similarly (and unfashionably) low opinion of ancient Egypt. Egypt, he tells us, was not nearly as important a civilization as everyone thinks. This is because Egypt was relatively poor in the sorts of inventions and innovations that are influential and useful for other civilizations. In other words, Hart's criterion of the worth of a civilization is its material contributions to general human progress. Which means that the internal structure and inner life of a society, what it is subjectively for its own members, is of no interest to him. Because the Egyptians did not add a great deal to civilizational advance, ... they are of no importance to him, even though, as many other observers and students of Egypt have seen it, the Egyptian society achieved a kind of perfection. The Egyptians experienced their earthly life as so beautiful, pleasant, harmonious, and stable (as one can glean from their paintings), that their idea of the afterlife was to continue in that experience forever. Once we understand this, the Egyptian cult of the afterworld, with its mummies and monumental tombs and pyramids, starts to make sense in terms of the Egyptians' own experience of life and of eternity. Seen from this perspective, the pyramids are not just very large and very impressive structures, they are representations of the cosmos. Of course this Egyptian culture with its focus on eternity was not as innovative as, say, fifth century Athens; indeed, it led to a static conception of society with little room for human freedom and creativity. But at the same time it represents an awe-inspiring human achievement, which explains Egypt's continuing hold over men's imagination.
In other words, Hart misses the Egyptians' experience of order. Every society and civilization is an attempt to create order, an orientation of men's lives toward nature, society, and the divine, which will be different in each society. But to grasp a civilization's order, we must attempt to see the civilization whole, and this is impossible if we reduce its meaning to a comparative list of its material and even its intellectual achievements. What was most remarkable about the Egyptians--and what still draws us to them today, even if we can't explain the nature of the pull--was not this or that achievement, but the underlying vision of order that each of those achievements expressed. A materialist will have little interest in all this. It doesn't come within his ken. He wants solid, useful accomplishment and that's that.
With the obvious caveat that this assessment of Egyptian civilization applies more to the Egyptian on top of the social pyramid than to the poor bastard down at the bottom, this is a good point. But I also admire Hart's reductionism. With history, you can profitably move in both directions.