I think it has to be done because many of these districts were ordered to be created by the courts in an effort to help the Democrats flip the states. If a district was created as a racial majority district by a court it needs to be brought to court by the DOJ and challenged.
It gets politics and race entirely out of the picture and reduces the travel distance for candidates and representatives.
As I have posted about Maidenhead Grids, I've noticed folks from all parts of the political spectrum are for it, nobody against it.
I just now finally found a good explanation of how it and the sub squares works. Grid Square Locator System Explained