With Nintendo not having an E3 press conference - which would be great mass media exposure for WiiU - I can only assume they feel they don't have anything to present that will attract attention away from Sony/MS's announcements (and both of them will have already announced their new console's pre-E3 so that'll put a damper on their own E3 presentations).
More significantly, I expect it means they have nothing that they think can generate sales with the casual market (it goes without saying showing more 3d Mario, Kart, LoZ:WWHD, Pikmin 3, will appease Nintendo fans - and there's almost nothing they could pull out of their hats to pull over Sony/MS fans now).
They can do all the ND and closed meetings they want, it won't sell any systems to the mass market that adopted Wii so readily. It seems a concession that WiiU was a mistake in principal. It has limited appeal and they just don't have any great game ideas that'll sell the gamepad (NintendoLand was their best efforts and came up way short).
So they're going to focus on their core market (not the gaming core, the Nintendo core) until they have a successor to WiiU. This is great news for Nintendo fans as the best way to drive up WiiU sales now is by giving Nintendo fans exactly what they want. It's bad news for investors though as WiiU will struggle to meet or exceed Gamecube sales level without the casual consumer.
Re: Wii Fit U and Wii Party U. If Nintendo had faith in these titles to sell to the mass market or Wii crowd, they'd be front and centre in an E3 press conference. That's not happening and they won't sell via ND that should be obvious. I don't think this is Iwata's gut talking, I think this is a lot of market studies with actual casual gamers who just weren't impressed by those games, or more likely. needing to use the gamepad to play them.