I don't think it's really aimed at Amazon Prime people.
I think it's really to get people to order more from Amazon, even for orders <$25. Tote will probably cost them enough that those orders don't make them anything, but it will build loyalty (and they let you keep the tote bag--keeps Amazon in your mind).
Will it really cost them that much more though? Since they assign your "Tote Day" for you, it seems like they could save a ton of money on the efficiencies gained in their delivery/location scheduler.
If you're using the service it looks like you'd get a much easier way to do returns. What I'm wondering is if it works in apartment buildings. If it does, I'm all over this.
I'm not sure their is a benefit for the customer other than hoping Amazon will pass the savings on in the long run. However, this service might some what eat into the revenues of Amazon Prime.
Also, Amazon Prime is not available everywhere, for example it is not available to Hawaii.
Edit: I have had 3 Amazon packages arrive in one day - one by USPS, one by FedEx and one by UPS. I get mine at work, so I'm not bothered, but I can imagine it is a convenience for people who have to answer their own door for packages to know that everything will arrive in one go.
You know what would be kickass, is if they offered a small discount to Prime members who opt to have the item delivered in this fashion. 2-day delivery has got to cost them more.