Beyonce was brought in to sing the National Anthem to the President and to the crowd of people who were there to watch the inauguration. If she didn't want to sing it or was not prepared to sing it, then she could have just as easily played a recording instead of pretending to sing. That is just insulting to everyone there.
It's amazing to me how much attention this is getting. Why does it matter? As long as the performance went well, and the president was happy, who cares? She's a talented woman, live or not,and really, as a nation, don't we have bigger issues to wrestle with? It doesn't matter one bit if she was live or not.
Beyoncé hadn't practiced with the military band and had she sung live, it could have wound up awkward, badly timed, or completely disastrous. It was still her voice people heard and her not performing live wasn't about her being lazy or unprepared, so I do not think it really matters that she didn't perform live because she did record the song, it wasn't as if somebody else was singing.
I know that people want folks to sing live, but we've got to consider the weather here. Her voice would have cracked like crazy, no doubt, and she could have potentially put a huge damper on the inauguration.
On top of that, it doesn't seem as though faking it is all that new to the inauguration. Along with the stories of her not doing her singing live, there were also stories of people doing air violin a few years ago and the band that was with her not playing their instruments live, either.