Another fun reason for wireless charging -- sometimes it's just easier to sneak power into the device by a side-channel than to try to find the right chain of adapters.
On older devices wireless charging usually doesn't provide enough power to sustain the battery level while working though. Because very few of them have Qi quick charge.
Pedantic nitpick to say: USB is a serial protocol, but video is not serial? It's a Displayport or Thunderbolt connection, using a USB-C-shaped connector and cable
But since it doesn't support charging while in OTG host mode, it cannot stay plugged into the adapter for long (old battery)
Some newer devices like Samsung support ACA OTG (Accessory charging adaptor)) with charging while powering the adapter