I think ability to disable battery status is critical, but not for the reason you might think.
The feature is incredibly useful in kiosk type applications, and I would hate to see it go away, but at present, it's not an official web standard and many are pushing to kill it. Firefox already has.
It's not really useful if nobody supports it, so there should be an official position.
And having it behind a setting sets a good example for the whole web on how this kind of thing should be handled, with respect for both those who need privacy at all costs, and those who want to take advantage of advanced features in unusual use cases.