I did leave out the religious analysis (more marketing, really). And it is true, except for the Islam-specific passages. The contant background advertisements for JihadTM make the letter look like it was written by the West's own propagandists. And perhaps he is (was) one of them.
Osama bin Laden was a believer in Islam, it was important to him, as it is intended to be for the reader. That such an appeal was missed by you and maybe even most who've read it is besides the point to persons like him. He felt he did his duty to warn of an attack, and appeal for a conversion to Islam first as his favorite experts suggested.
It is a logical analysis of American atrocities committed against the rest of the world. These atrocities have created the critics, and they are probably a majority of the world's people - and for good reason. The rest of the world doesn't experience Death-by-American-arms as a tweet that they can argue with. They experience as the destruction of their quality of life on this earth.
So that's an interesting point; I'll even make an opinion poll about it.