Only because the government has gotten so large that a shutdown affects so many people. But that is the way of a military and welfare empire, which is what the United States has become.
Because our money is really bank credit, all money is borrowed into existence, the government must continue to raise the debt ceiling. A bank credit-based monetary system requires more and more borrowing to survive.
If the citizens and the government were to try and pay off all of the outstanding debt, two things would happen. 1) we could not pay off all the debt because all debt has interest and there is not enough money to pay the interest component. 2) we would destroy the money supply. If we p[aid off all the debt, there would be no money in circulation and we would have to revert to barter.
As the US Government (and really all national government with central banks) continue to devalue the money, the system will continue to slowly unravel. We are watching the collapse of the bank credit-based monetary system as we know it today.