The argument needs to be kept in context and if you were with a company that introduced a new device that looked like nothing else on the market at the time, and then a year or so later a lot of other devices started pooping up that looked like it - what would you do? Just say oh well, it's just a rectangle that's obvious and bound to be copied so we'll just let it go..? I don't think so.
I've worked for a well known design company in the past and I know what goes into coming with something (hopefully) original. I've seen people do it. I've also seen them say, hey that's too much like Product X we need to do something more unique and better. Looking across Samsung's cables, headphones, docks, and even stores, they didn't have to consider that. They just took what someone else did and tweaked it (sometimes) a little and put their name on it. The designers I worked with would never have done this. They would have been fired for it as well.
So all in all, the 'black rectangle' argument in my mind is just complete bs. There's a lot of work that goes into designing 'a thing' and Apple took years to come up with the iPhone. Ultimately people noticed and rewarded them. And so has the jury. While our patent system may suck in a lot of ways, this was a big win for design and physical form.