Actually, from a linguistics standpoint, it is still argued whether ebonics is a form of slang or a dialect. I am going to have to side with dialect -- it is a variant of English, but bears enough differences in vocabulary and grammar to exceed slang. Furthermore, it is spoken by a small, ethnically distinct group (not counting middle-class whiteboy posers), which reinforces the categorization.
To assume that speakers of ebonics are lazy or uneducated smacks of racism. Language evolves based on time, geography, and social structure. Given that, in America, throughout the 1970s and 1980s, the rift between blacks and the rest of American culture, it is not surprising that jive eventually evolved into a standalone dialect.