I don't think the success of failure of Wii U rests on whether or not Ninty should have secured GTAV.
If they got GTA V Wii U would not sell substantially better than it already is. Not having GTAV is not causing Wii U to sell worse than its market potential.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix