I never knew about this change, either. I bet they had to do it to make clearance for the doors to go over the regular wheels. When they went to the 300 series they just ditched that kind of wheel but lowered the cart bottom. That probably didn't help with rust, either.
I am about 6-1, so I do like the higher stance. The 300s also stand taller which is part of what makes them look so much larger when in fact they have only a moderate amount of additional grilling space compared to the Silver/Gold/Platinum grills that preceded them.