I see this letter as an attempt at vindication for the controversy sparked by the NYT article on Amazon's corporate culture. Jeff Bezos was clearly affected and I see this as a defense of their "distinctive culture". "For better or for worse" that culture got them to $100 billion in annual sales faster than any company in history.
I live in Seattle and am friends with a lot of Amazon folks. Most work very hard and complain from time to time, but I only know one who left for another job because most who are there now actually really like their jobs. One friend put it best after he transitioned from a small department in the ecommerce side of the business to one of AWS's early-ish hires, that most young departments have the thrill of working at…
Amazon's culture is highly polarising. The emergent properties of which are all the truths and lies you ever read about the place.