Actually, as long as we are splitting hairs here, the Richter scale is a base 10 logarithmic scale which means that a 2.0 is 10x as powerful as a 1.0. Additionally, if you guys really want to end the argument over bigger brakes all you have to do is look at the equation for torque, torque=(length of lever arm) x (Force applied)(Sin theta). Since the angle relative to the lever arm is perpendicular in both case you can ignore the Sin theta portion. This shows that changing the length of the lever arm to 338mm from 319mm will increase stopping power by 5.9%. (338/319)=1.0595. So, it certainly does increase stopping power. The question is, is it enough to worry about?
It must be a big enough difference that Toyota designed bigger parts and used them, vs using the same brakes on all models. I'm sure in there bottom line there was a price difference.