Sony RX1 - the winner is Fuji X-E1

The 35mm is not for compact size reason, 50mm Sonnar is smaller, check Zeiss ZM lens. I think they choice 35mm focal length because it is good for general purpose usage. The 50mm is a bit more zoom in and not ideal for wider landscape shots. That is probably the reason Leica X1 and Fuji X100 choice that focal lenght as well.