As a listener, rhythm is extremely important to me. On a wider scale, the contribution that African culture has contributed in this regard to the world (and to my enjoyment of Jazz, Rock and Blues) is unquestionable and profound.
However, for me, rhythm alone is not enough to hold my interest. Melody is even more important. And the colors and shifting tensions and resolutions provided by harmony please my ear enormously. The sophistication of melodic and harmonic elements, coupled with infectious rhythms, is what drew me from Rock into Jazz in the first place.
The fact that Rap is the dominant genre, worldwide; that Rap is relevant; that Rap practitioners have garnered prestigious awards, have no impact on my response to Rap as a listener. There are other genres I find equally unengaging that can boast of their own particular attributes.
As vibration, music acts upon us on a variety of levels/aspects, simultaneously. The left brain is only one of them. If this were not true, then the facts you list regarding Rap would ensure that I enjoyed the genre. Obviously, this is not the case; we also experience music physiologically and emotionally and our tastes are conditioned by still other factors, as well-- some that can be difficult to pin down.
I’ve expressed my fondness for melody, so why don’t I enjoy every genre that has strong melodic content? We may try to justify our subjective preferences with objective rationales and they may hold up to a certain degree, but they do not tell the whole story.
