Funny enough, I had pretty much the same skepticism as the author re: Amazon Key. With IOT "security" scandals floating by seemingly daily, this feels like a poor tradeoff.
_However,_ this product seems like a great opportunity for a small hack: install the whole thing as a locker/bench/cabinet on your front porch. Almost all of the convenience, and no increase in risk. In fact, I'm a touch surprised that this isn't how the product was conceived and launched in the first place: as a personal package locker.