Sliding faceplates: why?

As modelled by the Sony T-Series and the Casio Exilim V7, among others. But what's the point of them? They open in your pocket more easily than a power button turns on, they add bulk to the camera, and they almost always come with a lens in the top corner that fingertips can sometimes carelessly wander into.

Anyone own a camera with a sliding faceplate? Has it made your life better?