Look closely. Steve couldn't bear the thought of a power button in the casing, so he HAD to move it into the F row of keys, and something had to be sacrificed. Unfortunately, that something was the keyboard backlighting.
So it was yet another pure form over function move, and a pretty dastardly one at that IMO.
There are two scary parts about the way this was done:
1) It looks doubtful that they will be able to put the backlit keyboard back in later as you might expect to make everyone feel they NEED to upgrade to the better, new model, unless they want to add another key to the F row, making them smaller, which I doubt they will do because then it wouldn't be "full-sized".
2) Expect the power button to migrate into the F row on the MBPs during the next redesign down the road. What do you think will be sacrificed?
I think in the next redesign, we will lose the optical drive, get the F row power button, and get a wedge shape.