There are some talented writers and producers who would never be able to front a commercial band in a million years. There are also physically attractive young people who can sing, sometimes dance but who could never remotely write a song by themselves or say anything meaningful. People in both groups want to make money and teenage girls want to listen to uncomplicated music made by physically attractive people. It's not complicated and sometimes, as with Girls Aloud or NSync, it results in bangers.