Changing many power settings changes for both "Plugged In" and "On Battery"

This may not be a "bug" per se, but I would think that many of the power settings should be modifiable based on whether on battery or plugged in. Currently only "Suspend when inactive for:" is based on power status, but really screen brightness, automatic adjustment of brightness, and how long until display turns off should all be able to be modified based on whether the system is running off of battery power or plugged in, since each of these settings in particular influence how quickly your battery will drain.