Not only is that low for a Dragon Quest game, it's not exactly the boost the Wii U hardware so desperately needed. The Wii U only sold 22,829 units last week, behind both versions of the ever-popular 3DS (Luigi's Mansion 2 was the best selling game, and Animal Crossing: New Leaf is at #3, approaching 3 million copies life-to-date), and behind even the Vita, which is experiencing something of a resurgence.
The sales situation for Dragon Quest X is more complicated than it may seem. While the retail sales were disappointing, there's likely a significant number of digital sales, which wouldn't show up on Media Create's charts – and which we'll never know about unless Square Enix or Nintendo decides to tell us. Square Enix offers half-price downloads of the Wii U version to anyone who owns the Wii version, so it's safe to assume at least some of the Wii buyers took advantage of that offer.
Of course, that still didn't move many Wii U systems, clearly.