Seeing The Keyboard With Light From The Screen
No idea why so many people have an issue with this. The light from the screen means you can pretty much see 95% of th keys anyway...
There are two points I would like to make relative to your comments:
1) I wonder if you are assuming that the user has a relatively bright screen setting when you say '95% of the keys are visible from the screen's backlight'. When I am using my MBA computer in complete darkness (in bed), I have the brightness set to 'one square' (and, in fact, I wish it could be even a little dimmer). At 'one square' of screen brightness I do not consider 95% of the keys to be ledgeable.
2) I am a touch typist. I know where all of the letters and numbers are. It is the special function keys that I often need to see (eventually I may remember where they are). These are, in general, the keys that are also less visible in the dark when relying on light from the screen (and possibly the 5% you also consider not visible). These are the ones I need to see!