it's a class thing, and you've maybe got the causality backwards. lower class white dialects are also viewed in a rather derogatory manner. and, it kind of goes back quite a ways in english. we have this collection of words we're not supposed to say. these are words that developed in the common vernacular of english, often from norse or welsh, and were rejected for deviating from the correct, aristocratic anglo-saxon version of it. scottish dialects remain widely mocked as well. judging people by the way they speak is a way to enforce class divisions, rather than a cause of them.

personally, i'm in favour of abolishing collectivized grammar altogether in favour of purely individualized expression. there's a kind of gramscian argument, there. the enforcement of correct modes of grammar is equivalent to the enforcement of correct modes of thinking. you could look at the rules of capitalization as one example of how grammar enforces the status quo. stepping back from that and allowing children greater freedom in constructing their own grammar conventions will allow for a wider range of individual expression that would be much more difficult to encapsulate into hierarchical categories.

for that reason, i think linguists need to be careful about how they approach ebonics, or whatever you want to call it. there have been periodic calls for this to be taught in schools and enforced as a cultural norm. but, the result of that is that it is going to enforce a hive mentality and then be used to further enforce a black/white class distinction. the path to equality is to abolish these sorts of distinctions, not to further cement them.

while integration has certainly not proceeded at the level that one might have predicted after brown v board, ebonics is not entirely a black language, either. whites raised in lower class majority black neighbourhoods in cities like detroit will speak in roughly the same way that the people around them will. policies that aim to mix it up a little and break down the association of dialect with skin colour will help in removing it as a tool of racial segregationist thinking, even if it doesn't take it out of the toolbox for class oppression. breaking down that perception and partial reality of ebonics as a "black language" is probably the best way to start.