According to Sony Worldwide Studios President Shuhei Yoshida, you won't be able to turn off the light bar on the DualShock 4, but developers can.
Here's are the tweets from Shuhei Yoshida:
— Shuhei Yoshida (@yosp) July 5, 2013
— Shuhei Yoshida (@yosp) July 9, 2013
Hopefully developers will include an option in their games to allow players to turn it off. I would imagine it would be very annoying to not be able to turn it off, especially when playing video games in the dark.
What possible reason could they have for forcing the light bar to always be on?
Source via Twitter