I find this piece to be a bit too cynical. As a kid, We are the World made a powerful impression upon me. I wouldn't have understood the causes of the famine had anyone explained it, but it did make me aware of large scale global problems, hunger, and charity.
Charity requires optimism, and some naivity. For me, the most important thing about We are the World, is that it was done. It might have been a drop in the bucket pragmatically speaking, but psychologically, it was done.