What is the big deal about Pre-check? I got it at ORD a few weeks ago, and opted out. I have artificial hips and always set off the WTMD. When I approached the checkpoint, I still had to take my shoes off, belt off and the only benefit was that I could leave my computer in the bag. When I set off the WTMD, I had to get patted down like everyone else . . . You'll forgive my obtuseness, but what does this do for me??