I would agree that the name hurt ZombiU more than anything. It's an in-joke, and a clever one, but it makes it look like the ultimate generic trash shovelware. Instead of being a very unique game.
Past that, its rushed development time probably prevented the game from featuring stuff like developed characters, cinematics, etc. It is a lean game designed to work around its limitations, such as using PA systems to communicate with unseen "preppers". But not the kind of thing to make hoards of people rush out to buy it and an entire system just for it.
Nintendo shot themselves in the foot with the online thing. They made it way too cumbersome on Wii and DS. Well, the 3DS is still bad, and I haven't played a WiiU.
I love online play, and I only ever went online with the Wii and DS a handful of times.
Online play on Wii U can be comparable to PS360. Black Ops II is fully featured and does not suffer anything. Right now, Wii U is closer to PS3 with its lack of universal cross-game voice chat, though it is more expandable in terms of OS than PS3, so that may be addressed.
The bigger problem with Wii U and online may be a chicken-and-egg scenario. Nintendo doesn't have an online ecosystem by PS3 and 360 standards, and kickstarting one from scratch is difficult.