I think this comes back to Nintendo trying to avoid risk. Similar to how they don't want to sell the hardware at a loss, they want to make damn sure that the production facilities producing the hardware are worth the cost in the long term.

They probably figure that the money lost due to not quite meeting demand is less than the risk to ramping up production to meet demand that may drop sharply over the course of a year or two. And it's not like starting up a production facility is a small task.