Sorry for offending your sensibilities, but as I said before I really like shitting on altars and public pieties - and pop-Kultur is one of them. It is like B/D: some like it, others are offended by it. C'est la vie.
You also seem to miss the forest among the trees by insisting that I consider 300 years of history of pop-Musik. Such rich narratives might be amusing, but are usually unsuitable for a more analytical approach. An analytical approach necessarily depends on comparisons that selectively focus on the relevant, from the argument's point of view, feature - hence the "cartoonish" character that irks you so much.
What is more, comparisons often utilize the concept of structural equivalence, which in short, means accounting for the fact that elements that appear different on the surface may play a similar role in the larger whole or context. Thus, in the example you cite form 300 years ago, the condemned persons being executed and the songs about them - albeit white by skin color - were structurally equivalent to the role played by blacks today, namely of "beastly, brutish underclass" as opposed to "cultured, civilized gentry." That structural equivalence renders your example quite useless to the point I am trying to argue.
So the bottom line is that I tried to use selectively picked cases to generalize to theory rather than to the population. That means providing empirical examples of a hypothesized relationship, rather than claiming that the examples represent a certain class or a population. My argument remains valid even if the examples I cite would be only two existing in the entire universe.
To counter it, you would need to show a pair of cases that contradict the relationship I claim - i.e. appreciation of cultural forms that run contrary to popular stereotypes (e.g. a black musician being exceptionally valued at performing "white" music - a Tiger Wood of classical music if you will - or a female artist seen a superior to male artists in the "male" genre) - which you must admit are really difficult to find.
Wojtek