How can you not blame Iwata for the company's missteps? He runs the company. At the end of the day he's responsible, good or ill. Nintendo doesn't get along with third parties? Talk to Iwata. Game draught? Iwata. Overpriced hardware? Iwata. He's at the top of the totem pole. You don't think Square Enix isn't blaming Yoichi Wada for their crappy performance? They are, that's why he's out. Iwata is a CEO, he's no different. He's an executive that can be removed if his performance isn't up to snuff (just like Reggie, for that matter).
Also, Don't confuse the sales success of Wii U with the console being a success for YOU. I'm not saying Nintendo fans won't love Wii U and enjoy the heck out of it; of course they will. But when we're talking sales, Western developers are driving sales on PS and Xbox, and that's a big chunk of the North American sales pie that Nintendo is inexplicably opting out of, whatever the reason. I don't understand that at all.