Aqua Japanese website, videos, pictures and more....

Agree with your questions. I know there are differences in dimensions between the two, but a reason why?

The good part of the 17" wheels is looks and allowing to fit wider and less drifty tires (lower profile).
The bad part is mainly economical disadvantage: cost of a wheel, cost of a tyre, cost in MPG, and cost in higher wear (215 go faster than 195). But also comfort (stiffier ride), which gives many people a reason to drop Prius for another car (know one that got fed and is looking for trading for a softer car, even out of the Prius family).

 

Reduced production costs and customer dissatisfaction. A la carte used to be the norm in car ordering, but try to imagine if every vehicle going down the line was slightly different with hundreds going by every day. Some models still have the option, but they are usually a higher priced, low production model where the plant has the luxury of keeping the pace down to get things right.

It still might possible with some makes and models. It can be done at the dealer for most full size trucks, but at an increased cost. It might not be a flat out price, but discounts on option packages.