The issue I see with your rationale of strong black teams suddenly becoming horrible and weak white teams suddenly become good, is at least it is only a one year deal for the few teams where that may happen and the next season they would be moved based on performance. But in the interim the parity is based on season long performance, minimizing the cheating that occurs when orgs bring in ringers for the parity tournament - for which there is zero way to control or accountability. We could make up all kinds of scenarios, but using prior season performance as a basis so allocate some of the teams to each divisions at least adds transparency to the process.
The problem with parity is the way it's run not when it is.
They have to many teams playing 4 random games over one weekend seems more like luck of the draw .
The elite 9 does it the right way over multiple weekends and you have to win your way in.