[derefr]

Apple's logic: the Lightning jack only appears on accessories; while the USB-C jack only appears on "computers." There's no Lightning-to-Lightning cable, because it makes no sense to connect one "accessory" to another. All "accessories" come with a Lightning cable, which is USB on the host end for now (because most people don't have computers with USB-C yet!) but will likely be USB-C on the host end in the future (and then you'll need to buy a reverse adapter—female USB-C to male USB—to connect it to old devices. Those will probably be common enough across brands once the USB-C-only accessory market picks up.)

All that being said, it'a interesting to use this logic to deduce what Apple does or doesn't consider an "accessory." The iPhone, iPad, iPod? Accessories. The Apple TV? Computer! The port to plug it into a computer—for XCode provisioning et al—is USB-C! To connect to it right now, you need either a MacBook with its charger cable; or the new MBP, plus an extra C:C cable; or a USB-A male:male cable (rare!) plus Apple's "MacBook USB" (female-USB:male-USB-C) adapter. A male-A:male-C adapter would be great, but nobody has yet made one. The market is very nascent.)