There are many threads asking for DLC. Well I don't know if this will make you feel better, but Wii U games in general are struggling to get DLCs. Not just CoD!
Check this website out: DLC | Wii U
As you can see, Wii U has many failed attempts to create DLC for ANY GAME. You can't just blame Treyarch and Activision for our lack of content.
I don't know what you're trying to say. There are a number of games that have DLC on Wii U. It all just depends on which companies want to release DLC. I've bought some DLC. I may buy some more. It's like you're saying there is no DLC on Wii U which is incorrect. I'm not sure. Your second-to-last sentence doesn't make sense to me.