Because basic trade in-game currency should not be the answer to this... And well, it's just a joke asking what they are asking. For a feature such as this, specially after all the advertising they did about it, and how they said that 5 to 10 POOR people could buy the smallest one, lol.... Now it doesn't have to be that extreme, but it doesn't have to be that outrageous either. With the numbers Yoshida said in his response the big majority of the players will not get to even experience this content until a long time from now, when new content should be the boom, and not 3 month old stuff.
It has been said, they also said they were worried about reselling and stuff, but why even make a plot tradeable? The benefits should still not matter enough (like selling your own premade house, but that wont happen cause you can't sell it with stuff in it).
So it just seems like excuses.
