I figure that if the lyrics are really important,then they would be foremost in the song;which tends to happen anyway. Like,story-telling songwriters are almost always the most understandable,but if it's all about the groove then that's where the focus lies. I think that's why a good chunk of my generation (x) hates mumble rap. Hip-hop is usually about the story. But it seems that the words and music are all one sound (?).