If there's no advantage to using the default fire state (Return fire?), over Attack Ground, why not remove it and replace it with Attack Ground as the default fire mode?
There are times I want to quickly switch to hold fire, and back to firing at will, such as to force a target change to something closer more straight ahead of where I'm walking, or to force sort of a synced or cascade fire with long range siege units. Having to cycle through one more fire mode creates a hassle, and needing to remember to switch in order to use the attack ground adds a lot of clicks.