1. For people without a security system, there are many simple ways to get into a house. If you are worried about people getting into your house, you might not want this, but you better also already have a nice security system (that is also not on a botnet).
2. At least for us, we generally recognize our UPS & USPS folk that deliver to our house.
3. This has a log and video of the drop off.
4. Who do you trust more? The people delivering your package or the random person driving around the neighborhood looking for packages that would imply you are not at home? (or just grabbing your package)
All that said, usually someone is at home when we get deliveries so I wouldn't buy it (also don't use Amazon much). But I don't see the reason for the backlash.