and why did European settlers in the Americas, when presented with the direct juxtaposition of hunter gatherer lifestyle with their own often 'go native'?

Uh, going native is exactly what the vein of thought is predicting. The question is not why did some go native, but why didn't all the rest?

Farming solves military coordination problems that allow them to conquer neighbors. It would be a mistake to think that civilizations were successful because they provided a better quality of life for their denizens. We should expect to see the most successful civilization to be that which is able to devote a larger amount of wealth towards expansion.

An old suggestion, but just as old is the point that civilizations routinely fail at military matters: it's a trope of history going back at least as far as Ibn Khaldun that amazingly often the barbarians roll over civilization, and conquer everything, only to fall victim to the next barbarians themselves.