Knowing his motivation is impossible of course. But, I have to wonder if he is he entirely rational. Taking some of his comments over the years at face value (i.e. assuming he isn't lying), we have:
- overconfidence/narcissism, as not once has he consider stepping down,
- magical thinking of the 'if you believe in yourself, you can do anything' variety.
It is entirely possible that Iwata has never even entertained the possibility of wii u being a garbage product, or the possibility of him destroying the company through incompetence. There are people in the world who never doubt themselves, never accept failure as their fault, and never ever back down. Maybe he is one of those guys.
I think a lot of people are over dramatizing the situation on this board. Iwata is deeply embedded into Nintendo's culture, a figure that has operated inside Nintendo for more than 20 years. He knows the company, and he knows its people.
He is also responsible for one of the biggest success stories of all time in the electronic entertainment business. 3DS has been a relative success (well It started bad and quickly turned profitable). Now replace the Wii U with a system that isn't such a financial disaster and Nintendo would be in an average but much better place. It would be a still profitable - albeit in need of change - company.
That he doesn't want to quit - at least yet - is completely normal. It's not about the money - he has taken considerable pay cuts over the last years - but about ambition. I mean, if you had under you the teams that he has, for such a long time, wouldn't you want to keep trying?
To the people that say that he is oblivious to the issues with the Wii U, I don't think that any CEO of any company would say "well our product, the one that is out right now, sucks, that's what wrong". Any rational CEO would say "our product is good but there are issues and we need to fix them".
To the people that have mentioned the fierce competition that the Lifestyle/fitness industry poses, I completely agree with the idea that this is a huge challenge for Nintendo. But people seem to forget that this is the company responsible for Brain Training and Wii Fit, some of the most successful lifestyle/health products of I don't know, the past 10 years. Let's see them give it a go once again before we declare whatever they are thinking as a fluke.
Personally, I'm excited to see Nintendo pursuing things like unified accounts (a little too late, but they understand the need for this ecosystem), experiments with buying incentives, eg. And I want them to try to innovate in hardware. It is pretty clear to me that Nintendo can't compete with the money draining operations that Sony and MS have set up.
What I'm really worried at the moment is how they haven't rectified the Wii U situation. Between summer and Xmas I had a wonderful time with the Wii U, because every two months we had at least one major release, complemented with a couple of good digital releases and new virtual console titles. Now the schedule appears pretty barren, and I would like a 2014 Nintendo direct that shows me what exciting Nintendo (and non Nintendo) titles I should be waiting for, throughout the year. As it is, I only know about Donkey Kong, Mario Kart and Smash Bros. It is not enough, by far.