I understand the President's concerns, but I'm personally very comfortable with the language. There is evil in the world, just not of the biblical kind.
Yet still, who are we it determine what is evil and what is good?
(I guess this is taking a bit of a too philosophical turn, so forget my objections)
I'd assume there are certain basic moral and ethical principles that we can use to pretty clearly determine who is evil, based on our abolition of the slave trade,
this resolution, the Nuremberg Charter, the United Nations Charter, the Rome Statute, and the World Summit Outcome Document. There are obviously going to be some grey cases, but we can point to places like Darfur, Rwanda, and Iraq and say that those are places where evil happened.