There is no reason that Kanye West should not have been awarded an honorary doctoral degree. After attending the School of the Art Institute in Chicago and working towards this honor, he has earned his degree just as much as any of his fellow students have, regardless of his fame.
Universities have long used honorary doctorates to recognize the contributions to society of those in the field of entertainment. While not everyone agrees with Kanye West's political views or enjoy his music, his impact on and contribution the entertainment world is undeniable. University students can benefit from studying his life's work.
This honor was given for the School of Art Institute of Chicago. It's usually given for outstanding accomplishment in a particular field, so as a successful artist, Kanye fits the bill. When it comes to honorary PhDs, it is up to the school. If it attracts positive attention, donors, and students, why not do it? It isn't an actual doctorate and can't be used that way.
Kanye West might be talented and successful in his arena of music, but why should he be honored with a Doctorate Degree? There are many people who are famous that may deserve this distinction for their work in many areas. I do not think that "rap music" adds too much to the world, and I do not know of any acts of Kanye West that deserves this much honor.