You don't 'need' it because majority of WiiU owners don't even buy Call of duty. The Wiiu has an install base of 6.17 million compared to 4.3 million for Xbox One and XB1 can pull over 20,000 more players than wiiu. The case is, the majority that do buy COD on wiiu 'want' it hence believing the community 'needs' it. Also COD don't sell nintendo consoles and never has, so another reason to as why its not needed.
Here is a thought experiment:
Lets say that Sony and Microsoft both have the same version of CoD with the same kinda perks. The only deciding factor between the two is which platform you personally prefer.
Now, lets not announce anything for the console from Microsoft. We will announce it for Sonys console but wait in order to "build tension" and only have preorders open for Sony gamers. Next, we will use the low sales brought around from holding back any and all details for Microsofts console to say that we won't be able to bring any additional content (DLC). As with the lack of announcements and marketing, this is another factor that will lead to poor sales. Now, lets drop support early.
Which console will have the bigger player base?
The Wii U does not "need" the game and it certainly does not "want" another gimped and buggy CoD release. What it DOES need is equal support if and when the game does release.