I think you are losing it. Vagueness is not at all how I'd describe the controls in the Iwata era. Oohboy is probably right with experimentation.
To me, the Iwata era is Nintendo trying to move past button inputs to discover new control methods that might spur game development into a new direction. You had the bongos and microphone GC additions in the later GC era. The DS with its ideas of touch screen, duel screen, microphone input. The Wii with Motion control, the balance board, the updated zap gun. Although not from Nintendo, Guitar Hero and Rockband were able to benefit from this new game control experimentation that was going on. The Zelda games on the DS could have been done with button controls but they tried to experiment with a new control scheme by using the touch screen. Kirby had Canvas Curse. We saw Wii Sports, Wii Music, converting GC games to have Motion controls like Pikmin, Mario Power Tennis or Donkey Kong: Jungle Beat. This testing of new ways to play.
Maybe some of these things should have stayed experimental instead of being released but I think part of it was that Nintendo may have been unsure what the new audience would like or how they'd respond to such new ways to play and so they wanted to get the public's reaction. Even mixing motion controls with button controls was a new form of control. With this change in user input methods, I think Nintendo became unsure of what might be considered good or bad since it was new and unproven. Plus, the danger is that a program/software designer knows how their product should work or how they would use it but a new user can have totally different expectations and do things the designer would never have thought of. That's why there's debuggin and testing of programs and software before they are released. It could be the same with Nintendo where the designers could use these new input methods well or expected users to follow their expectation of how they would be used and it turned out to be totally different when actually released.
While this experimentation does seem to have toned down, it hasn't fully gone away. However, I see Nintendo trying to build on this past decade of ideas now and getting better at knowing what is working and what isn't. There wasn't much change in the 3DS from the DS and the Wii U is a furthing of the DS ideas along with Wii. This may also have something to do with developers and designers in Nintendo now being raised and trained on creating games with these input methods as well than older traditional button models. Hence why there was the "Mario Design School" we heard about with the release of all the New Super Mario Bros. games. While this experimentation can have a great impact when done right as shown by the DS and Wii juggernaut as well as the Guitar Hero/Rock Band impact that happened for a couple years, it can also be a great danger when it doesn't take off and can make a consumer wary when they are no longer sure what they may be getting or will be offered by allowing experimentation to run free.
There are some people who can go to a restaurant and continually try different items on the menu and some who will go and get the same thing over and over because they like it. I'd say the Iwata era is focusing more on the former and lesser on the latter and that may actually be a big part of the whole core vs casual gamer issue that arose in the Wii era than just what franchises or games were released. Look at what people consider core games, EA sports games like Madden, Fifa or NHL, Call of Duty, Halo, and others. They are games with very few changes in gameplay or style. Call of Duty could be considered an exception with it going from a WW2 shooter to Modern Day but since that change, it looks to have stayed pretty consistent from game to game but I've never played any so I'm just surmising. Still, that is the impression of core games on other systems.
You get to Nintendo where people consider core games to be Mario and Zelda and yet look at how much they will change things up on those titles. We've gone from Sunshine to Galaxy to 3D World and they are all different styles and changes in control methods. You could argue it is the same basic formula or core mechanic of running and jumping to the goal but compared to other systems, these are changes with varying responses by players to them. Zelda has gone from Twilight Princess (which I played on GC so I consider it traditional controls) to DS games and then Skyward Sword to more traditional with 3DS to who knows what now. You could call F-Zero a core title in that it has a great barrior to entry compared to Mario Kart, is more difficult and so is thus suited towards a regular gamer than one dabbles occasionally. Yet, Nintendo is reluctant to make another one unless they can find some new mechanic for it. Yet, Madden gets games released over and over, Call of Duty has games released over and over without trying to come up with new gameplay mechanics. F-Zero fans aren't asking for new mechanics. They'll take the same mechanics. They just want new tracks. Something that will test their racing skills. Although it could just be a way of deflecting that the series doesn't sell well and the Wii U userbase is too low to make an entry for it. Yet, Star Fox is finally getting a new entry because there is a new control method to be used for it. One of the odd exceptions is the New Super Mario Bros. series which has been blasted as being the same over and over. Yet, while it may be criticised for doing little to innovate, sales for it show that many gamers are happy to have the same old over and over.
Anyways, I've ranted on long enough. I was hit with inspiration and now I'm not sure I've made as definitive a point or statement as what seemed to occur to me so I'll leave it to others to pick over the pieces and figure out if there is anything worth following up on.