Historical context
The southern sound is more organic. It goes back to chattel slavery and the southern bible belt. The bottom line is our ancestors were very musically inclined and often used it to communicate and express themselves against oppression.
Those of our ancestors that were "fortunate"(I say that sarcastically) enough to migrate north had quicker access to the Europeans' education as freed men and women. This is essence of a societal disconnect that has been in place over the last 100 years. Northern "blacks" begin to feel like they were more sophisticated than southern blacks because of their access to european education and jobs.
The reality is.... they were no more sophisticated but they might've spoke Kingsmen English just as eloquently as their former masters.
Southern "blacks" were left with (european) religion, land, and were forced to work together (out of circumstance) to build communities because they didn't have the same access to the "best" (I say best sarcastically) education and resources as the northerners.
The south's run has been long and strong not because their music is simplistic or less sophisticated but because of it's origins.
Right. Y'all are musical. I think y'all said: why we sampling when we can just replay those songs or even create them ourselves, then rap on top?
Which is dope but not quite hip hop if you know what I mean.
And the reality of the matter is that hip hop culture to this day is strongest in the East. I've spent time in Houston, LA and New York. Outside of Atlanta, those are the biggest cultural hip hop markets in the country. And a friend of mine, Houston born and raised, is always complaining about how Houston as a whole aint really into hip hop like that.

That shyt came outta nowhere in 2010/11

at this point