sure, i mean, do whatever you want, of course. one reason would be that he's canonical. changed the genre more than perhaps any other post-2000 artist. + he's got (or at least had) a fiery passion unmatched by most and made some of the best rap music of all time
I think "makes great music" and "is an egomaniac" are orthogonal and the maniacal behaviors are mostly related to attention seeking, which is pretty important for selling mass media products. Kanye and Jack White are both legendary attention seekers.