So you asked some questions:
1) Can you really patent minimalism?
I think the box comes under trade dress, rather than patenting. And there are plenty of ways of differentiating -- Sammy's picture could have been of the phone at an off-angle, it could have been a picture in situ rather than contextless, there could have been icons emerging from the phone, etc etc. You just need to google "Android phone box" and you can see the endless creative ways there are of differentiating products on the shelf.
2) Can Apple sue because of a similarity in the box (vs the device)?
Yes, a manufacturer can sue (and win) because of packaging similarities.....because of your third question
3) Are Apple arguing the box is a significant part of the purchasing decision?
Yes. Same way that Coke can go after manufacturers who use the same shape bottle and the same labelling....and same reason that own-brand cola labels are so often red. Red = trusted brand colour for cola for many consumers. Apple are also arguing that the combined effect of all the similarities is what really counts in confusing the purchaser.
Re the cable interfaces. Just google images of "USB plugs" and you will see that the vast majority of USB plugs do not look like iPhone USB plugs. A typical USB plug looks like this:
Surely you can see how the Sammy and Apple plugs look far more like each other than either looks like this plug? In fact, you'll have to hunt pretty far and wide to find a USB plug from any other manufacturer, phone or not, that looks like Apple's or Sammy's USB plug.
Seems to me that you're not too sure of the differences between trade dress, design patents and utility patents.
As to the ethics of it, I think it's pretty straightforward. You develop a lovely shiny new toy that popularises some technologies that have been around and about for ages, but which no-one has previously been able to make come together smoothly. You put huge effort into making sure your toy looks beautiful and distinctive, so that people recognise it instantly and want to hold it. You launch it. Some other bugger comes along and copies your toy, including how it looks, so that consumers can't much tell the difference between the thing you brought to market and the thing the johnny-come-lately brought to market. Not very fair. That's the ethical case. It would operate the same way for someone who made a knock-off of an Aston Martin. Even if the engine under the hood was different, you can't just copy the same lovely body shape and pass off your car as being an Aston. It's Not On.