To be honest both the 360 and ps3 run Black Ops 2 at 880x720, but Wii U have no excuse since it released in 2012 and not 6 years ago.
I kind of have to agree, and I can only assume that Treyarch's game doesn't upscale at least on the Wii U because of VRAM issues with the textures? Disappointing to see, but then again I don't think anyone is really buying Wii U's to play black ops 2. I'm not willing to buy consoles anymore, but I would consider the Wii U before anything else on the market strictly because I liked Mario when I was a kid, and I like Mario now.
Technically, it's an inexcusable shortcoming at least for this game. But, Nintendo buoys its sales on nostalgic games anyway.