[hkuo]

The lowest brightness you can achieve by the standard Mac controls is equal to the halfway mark of this brightness app. So this app adds a huge level of control between that lowest setting and pure black.

I'm often unsatisfied with the lowest brightness setting when in a dark room, and this solves that perfectly. I just downlaoded it right now and tried it out and it works perfectly. I'd recommend you do the same as it's free before making judgment on it.

Edit: I just saw your edit, and I think you have it incorrect. Try clicking the brightness app menu bar icon, and then use your keyboard brightness keys to adjust, and you'll see at the lowest setting, it goes to the halfway mark.