I think the Republicans started dropping the dime on him before the media got to him. They really want to stop him from winning Iowa. The newsletters came up in 2008, but they didn't get much traction then, but Hannity brought them up this time to stop his growth in Iowa. If he wants to attack Republicans he would do better to go after Gingrich. Gingrich and Paul's chances of being President are just about equal.
You're right. I remember (I think it was Hannity) doing an interview with Ron Paul in 2007-08 and during most of the back and forth, it didn't take an observant person to see that Hannity was leaning towards "Buffoon" or "Whacky" with regards to Paul. I remember feeling bad for Ron and thinking, "Jesus, I guess Paul isn't Hannity's idea of a Republican."