My kvm, is in my monitor, a Dell U3419w.
One usb-c connection from my monitor charges / powers the laptop and provides usb connections to all my input devices, other devices, video, and etc.
Just one cable and I'm up and running.
My desktop is also connected to the monitor (display port and another usb connection) and I can switch back and forth as I need to. No cable moving or anything like that.
Keyboard and mouse are low speed devices that have little to gain from moving to USB-2 or USB-C. I'm sure they will eventually but there is no urgent rush.
Things like KVM switches tend to be low margin and target the lowest common/practical denominator in the marketplace. The manufacturers won't retool on a whim.