Because the Westboro freaks are America-hating a**holes who cheer when our soldiers are killed. (The Dove people in Florida are supporters of them and have marched with them). These are the nuts that protest at our soldier's funerals.
I don’t think they actually hate the United States. What they are protesting is that the US, they feel, has abandoned it’s Biblical roots and no longer deserves to be revered as a place of respect. This is most evident in their protests of military funerals where they voice their opposition to having homosexuals in the military.