The motive first became obvious to me when they formed 6A. After CG beat Whiteland I read an editorial saying how unfair it was that Whiteland was in the same class as Carmel and there was no way a school with 1,800 kids should play a school with 5,000. I read that and laughed because CG was 2,200 at the time. Forming 6A served Whiteland no purpose other than clearing some superior teams from its path. If it was truly about fairness or risk of injury then you don't leave the 2,200 enrollment school to play the 5,000 enrollment school.
The proposal being discussed here is perhaps a little better thought out but still has the same motive in my opinion.