I tried to do this with my current party. I asked them to tell me their character concept and I would help them build their characters. With the exception of the one I live with, they all handed me finished characters! I was able to help them fine-tune their characters, so I guess it ended the same.
My point is this: The player and the GM should co-operate to make a character. This way no-one is less powerful(unless they want to be) and no one steps on anyone elses toes.
IMO, YMMV
John Spencer