Nice, thank you. It also saves on etching wastes.
I've often used flood filled ground and power planes for reduction in etching wastes and milling time.
If you are thinking of extensions, I can see the use for setting the minimum gap spacing around specific traces for handling high and low voltages on the same PCB. I can also see the need for no trace void areas for keeping input and output voltages isolated as is done for PCBs used in AC line powered SMPS and isolated SMPS. No trace void zones likely being needed by more people. Not many hobbyists play with very high voltages on PCBs.