Looks like a ploy idea by tire manufacturers to sell more tires.
The tire manufacturers do not need to go to such extremes. The new low profile, wider tires that are used with the larger wheels generally cost over double what 15" tires would cost for the same car. They are also much more prone to blow out when hitting potholes and railroad tracks, and also give a rougher ride, and tend to wear out faster.
They put a larger footprint on the road, and that would make for better braking and control, but also poorer gas mileage. Of course, the larger wheels look cooler, which is why people want them.