People dreamed in color before television existed. The advent of black and white television made it more likely that you dreamed in monochrome, but people still did dream in color even back then. While yes, color TV began making people more likely to dream in color again, I'd say the real totally overall effect would be to say that "People dreamed in black and white for a while because of television."
The impact of the color of your dreams at night is debatable.