So what we have here is game design and systems targeting older core gamers, and presentation and art which appeals to younger kids.
I think this is only half-true.
Specifically, I don't think the game design/systems are targeting "older" gamers.
When I was a kid and way into videogames, Kid Icarus would be exactly the kind of thing I'd love. Frenetic action, lots of cool weapons and abilities, fast-paced, etc. I think a lot of kids are into that kind of stuff. Maybe my range for kids is larger -- but I think on the upper end of kids, like from 7-15, this is a game that looks crazy and fun.
It sometimes feels to me like people forget that they would play games like this when they were young kids.
That said, I do agree with you that Nintendo is going to have a hard time marketing this successfully. I think the key difference is not so much that the gameplay isn't suitable for kids, it's that the gameplay does not seem to be "playful" like the presentation/art is. But playful should not be thought to be a kids domain. Smash Bros. is extremely playful in both art and gameplay but it's a game that appeals across large age groups. Same with, say, Angry Birds -- very playful gameplay and presentation, but it's obviously popular with older players.
Calling it a day is what Nintendo did after the 3DS launch, where they had nothing big from March 2011- November 2011. Now that the system finally has a few games, you're going to start talking shit about Sony's performance? Really?
Calling it a day is what Nintendo has done with the Wii. How's that release schedule looking compared to that of PS3?
The difference with the 3DS and the Vita is this:
3DS: "
When are the good games coming?"
Vita: "... Uh,
are the good games coming?"
3DS has the benefit of inevitability. You know it's going to sell millions, you know it's going to get support. You know the awesome blockbuster games are coming because Nintendo is making them. It's going to get Mario soon, it's going to get Zelda soon, it's going to get Monster Hunter soon, it's going to get Animal Crossing soon, etc. etc.
Vita, on the other hand, is not so lucky. There's a genuine question of the long-term viability of the platform and if third parties, which are Sony's bread and butter, are going to commit to the platform.
As for the Wii release schedule -- the Wii has its successor coming out this year. Let me know what the PS3-exclusive release schedule looks like when PS4 is due out later that year.