The death of Hawaii's Senator Dan Inouye reminded me of what he used to say in defense of earmarks in appropriations bills" "They're not pork, they're glue. They keep the committee united behind the bill on the floor." In my experience, that was true. When members feel invested in legislation, they support it more strongly. The classic alliance has been between urban representatives who want food stamps and rural lawmakers who want the rest of the farm bill.
Friends still on the Hill tell me that the ban on earmarks in recent years -- despite some exceptions -- has made it harder for the appropriations committee and Congress in general to rally behind legislation. The 112th Congress has been the least productive in recent history, primarily because of deep polarization and hyperpartisanship, and the effect those conditions have on even routine legislation. Matt Yglesias even laments the death of pork barrel politics, despite his earlier concerns that logrolling was corrupting. I hope others come around to the same realization.