Allow different brightness settings based on external power supply state
A user preference for setting different brightness levels for the screen, based on the external power supply state, could be made available in the settings for the GNOME desktop. For example, a user could choose to have 50% brightness when the computer is running on battery power, and 100% brightness when connected to external mains power. This feature can be added in the Power settings panel (Settings → Power), where the screen brightness level is controlled. This would result in optimization of battery usage while not continuously dimming and brightening the display based on user (in)activity as is currently the situation. This is also especially useful for computers that don't have an ambient light sensor.
P.S. I had earlier mentioned including the keyboard backlight brightness too, but I removed that after realizing that the keyboard backlight level is usually preferred according to the ambient light available.