That's a bleed resistor to discharge the capacitor when turning off, else it could keep dangerous charge for a long time. ESR limits current inrush into the ca

That's a bleed resistor to discharge the capacitor when turning off, else it could keep dangerous charge for a long time. ESR limits current inrush into the capacitor, with ceramic caps you would need some additional current limiting. Voltage should not be that much of a problem, but there may be other issues with ceramic caps (like cracking due to thermal stress, voltage dependent capacity, microphoning, ...)