From the same article and comments below it:
"I am not trying to defend Britney, I stand firmly by the idea that there is no excuse for the lip-synching at this point in the game."
"The thing about the not singing part was basically this
everyone knew. But no one cared. The fact that we all paid 35 dollars to be two feet away from our idol was enough for us. Call it dumb, delusional whatever you want. But when the CD started to skip my heart dropped and everything was so unreal. Britney did look worried but she smiled when the cheering got louder and everyone went crazy. I think everyone in the audience needed to show their support as the pop idol crumbled before our eyes. But then Britney kept going and thanked the audience after the song. What Britney did next was pretty smart. SHE SANG."
Maybe she sings a little (not fully) while lip synching. It sounds like after this problem, she may have actually sang the next song live. Someone else said that she tends not to sing while dancing, but may sing live while doing ballads.
I'm glad that my favorite performer (Rick Springfield!) does 2 hours shows, live. He's amazing! I don't know that I'd go just for 14 minutes, even as much as I enjoy him. I know Britney Spears has a lot of fans, I just don't understand travelling cross- country for tiny concerts.