Obviously, this document is not from the Hakluyts, and while you haven't told us exactly where it is from, I assume it must be from Winthrop's 1629 justification for the settlement. Basically, Winthrop argued that God had intended for man to be fruitful and multiply, and to "improve" the land and natural resources he was provided with. Winthrop argued, as did most Europeans, that the Indians were not doing this. He thought (or said, anyway) that they were not making full use of the land. Of course, this view was steeped in an ethnocentric understanding of what farms were supposed to look like, as well as of appropriate forms of land use, but it was very common--perhaps the most common justification for expropriating Indian lands through the late nineteenth century. A variant of this view would later be expressed in economic terms by John Locke as the "labor theory of value." Winthrop also argued that the Puritans would bring Christianity to the Indians, but that was not as germane to this question as the issue of proper land use.