It's not actually stated that automatic braking is the reason for the change. It even gives a different reason: 'To create a "virtually smooth ride across the grid"'. They straightened out a step-shaped road into a straight one which is surely just a better experience for all cars and their occupants. I almost wonder if the vehicles that left the road did so by making a jump using it as a stunt ramp.
This article has before and after pictures from the same angle: https://www.somersetcountygazette.co.uk/farmer/18996741.catt...