Convenience is an ethical soundness, it just isn't usually taken that way.
Shifting commerce to digital and personal, just-in-time shipping, and customer-centric are good. Ugly business practices, creepy data mining, and DRM are bad. If you want to wave your hand at "conveniences", why wouldn't I wave my hand at "philosophical quibbles"?
Amazon is a mixed bag. For me, it's more good than bad. Putting your blinders on to the good for the sake of argument is not convincing.
I think I'm not understanding what you're trying to say. Maybe it's that small wins for large number of individuals outweighs large losses for small numbers of individual?
The OP pointed out a number of good things about Amazon. I took you to imply that these reasons are sellouts, and ethical issues are on a different plane than commercial considerations.
My take on this is that it's early in the conversation to downplay these wins as small (after all, why do people die of starvation today? Not shortages or money: distribution, which is a keystone problem for Amazon).
I also hope we will think of improving commerce as a moral issue. Assuming that it boils down to worthless materialism or Mammon is not a fair picture.
You're right in that it's not fair to write off the improvements to commerce. These will have a large, unforeseeable impact. That being said, from a North American perspective it seems that commerce is steadily improving while economic equality and working conditions are worsening. We're at the point in society where technology may have permanently made large swathes of people essentially redundant.
Is it really unethical to buy a DRMed ebook? Seems to me I only hurt myself with it - unless you count the bigger picture that I am contributing to a future where everything is DRMed. But I think the latter might be overblown. Even if people buy DRMed books, free books still exist.
Not sure about the sweatshop story, but at least with ebooks the workers have to sweat only once, when they ship the kindle.
* Cheap
* Consistent
* Fast shipping
* Good product availability
* Good return policies
* Vendor and item ratings