User blog comment:Callofduty4/Black Ops II coming to Wii U?/@comment-3050440-20120809200747/@comment-3171236-20120813174738

Treyarch actually was planning on making DLC for the Call of Duty games on the Wii, starting with Black Ops. However, Black Ops added new technology, and this caused some Wiis to break. When customers of these Wiis went to Nintendo for help, they blamed Treyarch's discs for breaking the Wiis. Treyarch responded that it was the Wiis themselves, not their discs.

Because of this little standoff, Treyarch canceled DLC for the Wii games.