At first, I wanted to develop this topic into something more than just criticism of phone cases. Most likely, there is something in common between a fashionable smartphone case, a rug on the wall, and a remote control in cellophane. Something very serious, embedded in the cultural code.
But let’s take the easy route.
A case is a device for storage, not use. You take your car out of its cover before you start it, and your glasses too. An exception to the rule might be a case that has some other function: for example, MagSafe in an iPhone or a case with a belt clip in a Nokia 3310.
The Nokia case, by the way, is a perfect example of how pointless the “protective” function can be. And while the analogy with a smartphone might seem off, protecting modern “sapphire” or Gorilla Glass feels even more absurd than wrapping a fragile old LCD in a sleeve.