Because it is a cash cow. 130 games on Black Friday did 10,000 or more on the Wii. That's a cash cow especially when you think about it as in Wii development costs are that of PS2 games and sometimes a hell of a lot less. It's a console where you can put multiple titles out and have 1 succeed and make millions while the others may only sell 20,000 and they may actually make a profit out of that but if not only lose a little.
It's a non risky platform for the most part so of course devs are going to do these kinds of things. And with popularity comes attachments haha. Hell what did you think MS was trying to do with Wii60. Other corps like to attach themselves to its success which is why no surprise that BK would have Wii related toys and what not.
