@garebear sorry, i failed to mention any of those artists you pointed out. because they're not. Please read more carefully. Also, your label of "typical lyrics and thumping noises" sounds like what Boomers' parents labeled rock. I guess getting old has the same cultural myopia no matter what generation you belong to.
And to @curtdr 's point about hiphop and rap being race related; well, it is to a large extent. Rap morphed into a language of social protest when PE came on the scene in 84 and really accelerated with NWA's social commentary starting in 1988. The art form is inextricably linked with social and political commentary across the globe; Balen in Nepal, Sendata in the Phillipines, or Ukraine's Shevchenko.
Just as rock was the art of protest 60 years ago, so has hiphop and rap become the same. It's just, as @perkri wrote, Black Americans have been subject to marginalization far more than other populations. Including, I assume, most Audiogoners.