I understand. This has also something to do with corporate identity. It was just an idea to improve this great feature.
I think the reason in using ribbons is that you can faster see, which type of article you have. With different colors you could see the difference between many articles in one view without reading the text of the ribbon. If you would add black as third color, you would get 6 variations:
black background/white text
black background/orange text
white background/black text
white background/orange text
orange background/black text
orange background/white text
How many article types do we have? News, reviews, sales?