He’s the leader of the wing of the GOP that craves media attention. I believe he assumed the post from Sen. McCain circa 2002. This Washington Post article from last November says it best:
Okay, now that the election is over, are you ready to talk about 2008? Chuck Hagel is.
The Republican senator from Nebraska has been thinking seriously about 2008 since he won reelection in 2002, and mulling a run for the White House even longer. He has a long history of doing, and getting, what he wants. He’s ready — well, ready to talk.