To add to other peoples comments, the problem is also the stubborn gamers on Nintendo system who punished the developers because of parent publisher decisions.
Examples being
1. Rayman Legends = was shunned because the game got delayed, when in return we got three other Ubisoft games announced (AC IV and Watch Dog and some other I forgot).
2. Need For Speed ignored because EA said they are pulling support.
Sure there were gimped games on Wii U but the following deserved to crack a million for their effort with the limitations the system had:
- Zombi U
- Need For Speed
- Deus Ex
- Rayman Legends
- AC IV
- MH3
- COD BO2
- COD Ghosts
- Injustice God Among Us
The fact that a lot of the Nintendo games on that list haven't even cracked a million just shows how poor the console is going.