Why not reduce the time the backlight stays on by lowering the timeout P24 of the manual
That goes out of the window whenever you get an alert or notification.
The backlight will come on and stay on.
If that is indoors or during the day you won't notice and the battery will be draining heavily.
The feature request stands. I have asked before also as it is a really bad implementation as it is.
It would make far more sense to have it as an activity setting as requested.