Huh, that is a good question. All cars use the same knuckle and lower control arm, so it's not like they parts bin engineered the addition of the CVT in the second model year and changed the caliper with it. Also, the exact same rotor for both of them. Its gotta be a weight thing, but why tool up a brand new part to make something heavier in the second year?
You're right, it doesn't make much sense.
Being the same knuckle and rotor, you should be able to swap the aluminum caliper on to a cast iron car. Assuming the piston bore is the same, and vice versa.