Well, good for you if that's enought for you. I tried every kind of external light I could find and nothing can compare with the smooth confort of the glowlight.
No battery to change, no light to move when I read the bottom of the screen, no low light when the battery is not quite dead but not good enough any more, no searching for the stupid light I left in my room when I'm not there. No anoying glare...
I'm not going back to a nonlit reader. I don't even use my Opus any more, I keep it only for emotional reason (it's a gift), and potential backup.