Did you miss the fact that they're green, not gold, black, red, or silver?
I think it basically comes down to a really good, lightweight caliper design. As the description in the link says, 5lbs per caliper, which is half the weight of the stock calipers. I'm sure there is some appeal to them being a part you wouldn't see as often, but I think whoever is interested in buying these is going to buy them for their performance capabilities more than if they came overnight from Japan. The combination of the calipers, circuit pads, and the rotors just works well together. Some people appreciate high quality, well-sorted brakes.