Flippers are still making it to the final every year so we dont want to make it over easy for them. I think if boxes were limited to 10-12kg that would be a good move, People wouldnt just be able to build and indestructable box and charge head on into spinners knowing they wont take damage. With the ground clearance thing its probably a good idea but will it make it too easy for the flippers against spinners? A horizontal spinner would still engage but if you had 3mm ground clearance under a vert spinner a flipper robot would drive straight under without been touched.