I felt like I wanted to go to HD sooner.
Even for the Wii, no matter how much it made the system cost, it would have been great if it were HD in the first place. However, it was going to take some time for HD televisions to become common and we felt that until that point was reached, there would have been no point for Wii to be HD.
From our point of view, once the subsequent generation to Wii came around, HD televisions would be more common and we felt it would be time to make our games in HD then. However, HD became more common about 2 to 3 years earlier than we had anticipated. A main part of that was that the prices for HD televisions manufactured overseas had gone down at an unthinkable pace.
So, as a result, while we were right in the middle of selling the Wii, the TVs in peoples living rooms (in Japan) were slowly becoming HD sets. Overseas especially people had never so rapidly and drastically changed their hardware to the newest technology but in America as well HD TVs became standard little by little.