You are all grasping on to different parts of a whole reason. Granted these companies each have their own agenda, but considering the facts that A. the games made by most multiplat publishers are AAA and B. Profit is the main concern of these systems.
The reason third parties would avoid the Wii U is obvious once you consider its predecessors and its current situation.
Simply put the restraints that Nintendo put on the 64 and GameCube made the power differential between them a lot smaller, it didn't matter if the GC was more powerful if its games were reduced in size. 3rd parties were at a disadvantage, competing against Nintendo's 1st party games which the system would be tailored for.
Encounter the Wii, which was indisputably under powered in relation to its competitors. Now 3rd parties were even more gimped because the power of the system was lacking, while still having to compete against games that Nintendo had the system tailored for. And despite the Wii's huge market share, many 3rd parties couldn't break even on porting the game because the profits were so small, i mean who would buy a gimped copy?
Enter the Wii U, above PS3 and 360, but once again underpowered compared to its competitors and of a different architecture that its competitors. Because of that the porting cost increases drastically. When considering the low sales of 3rd parties in the past, and the new porting costs, it becomes clear that it would be rare to make much money off of porting a multiplat to the Wii U, not to mention, its userbase is even more restricting.
AA games and indie games have smaller budgets so they would profit from being on the Wii U, but AAA games face to much of a risk
In this day and age, with the Internet, ignorance is a choice! And they're still choosing Ignorance! - Dr. Filthy Frank
