I don't buy third party games on Wii U because the games they put out are crap compared to the level of polish and playability Nintendo gives me. Assassin's Creed has a terrible frame rate compared to my PC. Need for Speed was awesome, Rayman was awesome, Mass Effect, Deus Ex, even Sonic are pretty good games. But other than those, everything has been gimped or treated like a second class commodity. FIFA was AWFUL. And of course EA used that BS to justify no more FIFA games. I AM THEIR TARGET MARKET AND THEY REFUSE TO SATISFY ME. Every year, I buy on PC and last year made me mad they didn't put Ignite into the PC release. Finally, they got it right with FIFA 15. But it's that kind of crap that makes me avoid third parties. Nintendo keeps proving that games can ship, complete, with no big patches or DLC required. Even the size of Nintendo games is much smaller than more system-intensive games.
I own 17 retail Wii U games, and much more downloaded eShop titles. I play PC games a lot, because we PC guys get the best versions of games most of the time. MOST of the time, not always. Why would I buy AC IV on Wii U when I get the better running version for less on Steam? That's a value proposition that Ubisoft needs to sort out, not Nintendo. Those who buy the games on Xbox and PS don't have gaming PCs.