I am curious what you would map otherwise?
A quick reboot option to get data at rest comes to mind.
missing-root Yes of course the quicksettings toggle is there. But it takes a few secods.
Some examples, riding a bike, or in a car if you need a flashlight, it is really dangerous to take that long. Long pressing on that standalone button works blind.
It is am immense usability improvement and also safety, a lot.
Rest assured that I understand this is not what you're asking, and you can feel free to tell me to put my advice where the sun don't shine, but might I suggest carrying a (very small) flashlight? There exist flashlights that aren't bigger than a finger and which will outperform your phone every single time, in form factor, brightness etc.
I do understand wanting to use your phone since you always have it, and depending on one's needs, it'll do just fine, but if you use a flashlight enough to need power button access to it, perhaps the right tool for the job is just what one needs!