Why is the TSA taking out nipple rings and pantsing amputees?

CBS2 Chicago has a good roundup on the trend to "X-rated" TSA searches at airports wherein travellers are forced to strip in public, remove their nipple rings; a child amputee recounts the humiliation of having to endure a full pat-down every time she flies:
In Chicago, people like Robert Perry are subjected to exhaustive security checks. He was patted down, his wheel chair was examined and his hands were swabbed, all in public view in a see-through room at the security checkpoint. Perry, 71, is not alone

"It's humiliation," Perry said.

Perry was also taken to a see-through room by a TSA agent when his artificial knee set off the metal detector.

"He yelled at me to get the belt off. 'I told you to get the belt off.' So I took the belt off. He ran his hands down over and pulled the pants down, they went down around my ankle," Perry said.

At that point, Perry was standing in his underwear in public view. He asked to see a supervisor. That made things worse.

"She was yelling 'I have power, I have power, I have power," Perry said. The power to stop him from flying to Florida with his wife that day to celebrate their 50th wedding anniversary.

Fliers Complain About X-Rated Security Screenings