Rap written down on paper could be called poetry. One of the reasons I do not listen to his music mutch is because it is to much like poetry to me and I do not really like poetry to much. Do not answer this, just think about it...... Have you ever really listened to more than what he had on the radio, hell did you ever really listen to that or go to a lyrics site and read it?
A singer can arguably be called a musician, a rapper while certainly more monitone than a singer with vocal range still uses his/her voice as their musical instrument. You would also be suprised how many rappers know about music and musicality, the fact is the way rap is produced sells, bands do not sell as much.
Here is a challange though. Since people who listen to "real" music tend to bag on rap so much I am going to start a thread and challange you so I am not killing the flow of this post here out of respect to its originator.