I just updated my Lumia 800 to 8107 OS and firmware (1600.2483.8106.11500). Now when I change my brightness settings to NOT automatically adjust, the soft keys are always OFF. They were - and should be - always on when you activate your phone.
I think it's by design. If you're using med/high brightness, you'll be in a a light enough place to see them them without them being backlight.
That is a stupid design if it was intended. Just because you have it in one setting doesn't mean you are in that one place all the time. Might as well removed the keys all together.
I would really like an extra setting for illuminating the soft keys as well...Then everybody would be happpy..
In semi-bright conditions (end of day with a bit of sunlight indoors), the keys are not visible and the screen is a bit too dimm in automatic mode. Because you cannot feel them, I NEED the visual clue with the light.