Every time I read a review of a camera featuring in-camera charging I find the manufacturer roundly criticised for not including an external charging adaptor in the box. Apart from the fact that these little gadgets can be bought on Amazon for a few pounds, I just do not see the resistance to in-camera charging. It is simply more convenient and a more foolproof option when travelling. Forget the charger for many cameras and you are scuppered unless you can find a good photographic shop. Forget the charger for a Sony RX100, RX1 or a Ricoh GR and all you have to do is find a USB cable and plug it in to any USB charger or, even, a computer.
If you wish to carry a second or third battery is is simple to keep them charged in the camera overnight. On balance, I now much prefer to be able to plug in the camera instead of having to remove the battery and place it in an external charger tray.
Incidentally, full marks to Sony for using a standard USB Micro plug for their cameras. I can share this cable with other peripherals and, if lost, it is easy to buy from most phone shops. Ricoh has chosen a smaller USB plug (shared with Nikon) which makes it more difficult to find; on the other hand it makes for a much smaller connections panel on the camera.