Can we continue the discussion under the definition of rap being the whole package?
Otherwise I am going to have to pull out some spoken word songs by dead white guys and start waving them around...
As I see it there are a number of reasons why some people don't respect rap.
1) the music in rap is largely sampled from somewhere else and then reconstructed. It is the first music of the information age. Some traditionalists, like Phil Spector, would say that rap arists should go and learn to write their own songs. Others, like Pete Townshend, would say that the traditionalists should just shut up and get out of the way as a new form of music has been born.
2) Subject matter. Much of what passes for mainstream rap is all about bling and guns and bitches. In answer of that, I point to what passes for mainstream pop music which, as far as I can tell, is all about people expressing soppy love sentiments at each other. Neither is really all that good when it comes down to it. It should be noted that this has more to do with content than the form.
Interestingly, many of the comments I see that complain about rap music "sucking" are not all that different from the kinds of complaints that were once made about Rock 'n' Roll.