I feel like this is the heart of the lawsuit, and I certainly understand why one would file it.
The phone is a highly portable device, meant to be moved around. Because this motion is so prevalent, it stands to reason that there's a decent chance at some point, it will get dropped. Some drops are mundane, some are catastrophic, all based on the luck of gravity.
The phone is a fairly expensive piece of equipment. So, while a dropped wineglass results in maybe 3/4 dollars out of pocket ... this could be over $500.
I guess one would expect that the phone be able to sustain a couple foot drop and not sustain horribly catastrophic damage, because dropping it has to be considered a reasonable event. I've dropped my phone a number of times, on cement, and it's still pretty much ok. The case it's in maybe not so much.
So it's unfortunate for him if he hasn't put it in a case. It's a reasonable extension (but one could argue that you shouldn't advertise a phone costing $200 that destroys itself when you drop it, you should advertise a $220 phone (+ $20 for the case), that survives reasonable drops.
For me, I feel the same way about their laptops. I've owned three powerbook/MBPs made in the metal case and I've also owned three powerbook/MBPs that have sustained pretty substantial damage in areas around ports (twice around the charger port). The last time, I dropped my laptop off my shoulder onto a carpeted floor, in a laptop case, when the laptop was in a hard plastic case. and that really damaged the monitor out port. And I guess that's just a little surprising. That's a fair amount of protection to still result in that kind of damage.
I think sometimes what I wish is that for things like iphones and laptops, there be some effort to help them survive a reasonable drop. Similar to how cars work under 2.5 mphs. It'd be pretty challenging to make a car survive a 60 mph head on collision, but backing up for parallel parking shouldn't result in a mangled bumper or a flat out ruined car. I feel like the same thing could be said for laptops/phones.