Kanye West speaks his heart when he writes and performs his songs. They are not just 'numbers' that he wants to perform but things he wants to say, and to have the world hear about, mainly fair treatment of black people.
He has the skill to put his feelings and ideas into a structure that catches the spirit of the moment, and with the sounds that appeal to most people when they want music in their lives. He does have a charismatic appearance, and this obviously helps a lot.