Facebook may want to rethink their plans for offering users the option to pay to have their posts go out to more of their followers. One issue that it will highlight to users is that their posts are being filtered, their posts don't go out to all their followers, Facebook has some algorithm that filters who it goes to.
Another issue that it highlights is just how dismal the click through rates are, I've read some reports of people that have tested the system, the click through to promoted posts sent to people that are following users are at a very low rate. This clearly shows users that even people that follow you aren't really that interested in the stuff you post.
That is not a Facebook only issue, it is true with all social media sites, but making it painfully obvious won't help them much on the revenue front and will likely turn people off from using Facebook.