Zack and Wiki 2 is not surprising at all ...
I could be wrong, but Zack and Wiki seems like the type of game which would have had a very small development cost (in the $1 to $2 Million range); it was likely developed to experiment with a variety of Wii controls to see what the Wiimote could do. Zack and Wiki has probably already broken even, and will potentially turn a healthy profit when it is released in Europe.
Capcom knows that sequels from a game like this can potentially sell better because word-of mouth advertizement from a dedicated fanbase is a very inexpensive and high quality form of marketing. The 150,000+ people in North America who will end up owning Zack and Wiki are all fairly likely to tell people that it was a great game and they should try Zack and Wiki 2, which can lead to it selling 300,000+ units ...
