the one thing i've read about amazon's impact that made a lasting, positive impression on me was by a black woman who noted that when she shopped on amazon, no one followed her around the store. there was also some commentary on underserved communities where traditional retailers were reluctant to set up shop.

of course, this is really an argument for ubiquitous online retail rather than amazon in particular, but it was a good point in their favour. (sadly, it seems to be being built by exploiting workers, which is why i cannot take any claims of philanthropy seriously.)