I suppose you're doing what might be a resource intensive task and want to be sure you don't kill the battery.
Granted I get folks might feel a rando website that is resource intensive would be horrific, but maybe we're talking about some specific web app / use case.
Emergency tools could benefit from knowing if the device was about to die or not, like the Tinder SOS app, government emergency tools, etc. Imagine sending a quick POST request to save session state or whatever before it dies.
That has its own set of challenges -- now you have to design your game so that the battery indicator doesn't cover up an important part of the game. Also, what if the OS allows it to be configurable location/size, etc.
Thanks! I did not know about these before. It looks like a step in the right direction. Though what would be the next step? It seems like there would still the complexity of laying out all the controls/HUD (or other visual elements) in the game.
Mostly agreed. However, if the screen is split into the system area and document area, then the battery indicator could go in the system area, and the game need not know where it is; only the size of the document area needs to be known by the game (and not whether or not the system area is present, what it contains, etc).