That's basically an option to turn it off for people who accidentally click that button twice.
I'd like a double home click option added: a pref panel for all the things on the iPhone that use power. 3g, wifi, bluetooth, location services, screen brightness, and airplane mode. all conveniently placed on the same screen. that would make my iPhone usage so much easier since I'm always changing options to save battery life, or to use the iPhone as a flashlight at night.
That is a good idea. Like a power management option.