Because Facebook wants to lure 'serious' publishers in its platform. It has worked great for zynga and other games, but once again it will fail for 'serious stuff'. Why doesn't Facebook realize that their future lies in entertainment rathe than news?
I think the two overlap more than you think. There has always been a group of people in society whose entertainment is talking about the news, almost as a form of gossip.
With that being said, while the idea makes sense, the Facebook implementation has fallen flat.
