The opposite is also true: "I just wanted to shut down and go home, and now is when you decide to stop and delay the user?"

This is an old problem. Chrome solved it the right way by stepping out of the startup/shutdown dichotomy and doing everything in background. Just one of the many areas where Google ran circles around Mozilla (with the benefit of moving from a clear slate, and probably also of staying away from the Gecko clusterf*ck).