Michael, I both agree and disagree with what you're saying here.
First, I disagree with the idea that Miyamoto is holding back the game design or that Nintendo has failed in the new IP department since SNES. I think Miyamoto is still a wizard when it comes to game principles, and I think he's a great help to the dedicated team leaders that are making the games. I don't think he is the problem. Also, if you compare SNES (perhaps my favorite all-time system) and Wii, there are good new IP's on both. SNES had titles like F-Zero (an all-time favorite) and Pilotwings, but they weren't really a big deal. The game that really pushed boundaries and sold the system was Donkey Kong Country, which was a big new IP that captured the public's imagination. Wii of course had Wii Sports, Wii Fit and other Wii games which were new in theme, style and gameplay, and they of course were some of the biggest new IP's of all time. Wii also had Mario Galaxy - which although an existing character was an all-new style of game - and Xenoblade, an amazing new RPG IP. In terms of quality, quantity and impact, I think they are pretty close in terms of IPs, with SNES's greatest advantage being third party support.
But while I disagree with the idea that Nintendo has lacked new IP's since the SNES days or that its veterans are a bad influence, I do think in the very recent history there is an issue with Nintendo's software. Wii U (and to some extent 3DS) has relied far too much on existing and established brands to begin their life. I think Wii U desperately needs a new IP to grab public interest. I actually made a thread about it last week or the week before. Nintendo has done a great job in the past with NES(SMB, Zelda), SNES(DKC, MarioKart), N64(Goldeneye) and Wii (WiiSports, WiiFit) of making a new game that exploited the strengths of the system and pushed hardware. Wii U to date has lacked a title like that. If they want Wii U to be a market leader they need a new concept or a fresh take on an existing genre/franchise that will make people say "wow". I like my Wii U, but I haven't seen that title yet.
