So she has gone from ok to pretty good? Obviously, the drama/surprise was a big part of the emotional response. That is what these shows are designed to do. Just like in a good musical or movie or music video. They knew there was some potential there for great television and that she could sing.
My problem is you are tryng to downplay her talent because of the emotional setup of the clip and her looks. She would be considered extremely talented whether you could see her or not. A studio recording of her would spend hours making sure she was eq’d correctly and every note was hit perfectly. Only then would she possibly be able to meet your high standards of talent.
I said she's got a pretty voice. But look at this article. The first two paragraphs prove my point. It's all about the fact that she was frumpy and old and no one expected her to sing well. Even your comments contained phrases about how she didn't have training, had never performed before, etc. That's what makes it compelling. If the expectations were different, she'd be judged differently. She did OK. It was pretty good. Those mean the same thing. And like I said before, she has a pretty voice. But it's not as if her voice is a huge deal. Plenty of people can sing as well as her. And she couldn't hit the low notes in the bridge.
It's a cute, heartwarming little story. But that's all it is. Masterful emotional manipulation by the tv producers.