Not strictly true, Wii's success also translated into strong sales for non Wii-series software like Mario Kart, Twilight Princess, Smash Bros, Mario Galaxy, Donkey Kong Country, etc.

But seeing every one of those games performed no better than on systems with a third the install base, it really was Wii Sports, Wii Fit, MK Wii (motion controls), and NSMB (multiplayer fun, rare exception of non-gimmicky game moving units) that drove console sales. The lackluster legs of Wii post-2010 reveal this all too clearly IMO.

Still not technically true, Smash Bros sold better on Wii than on N64 or Gamecube for instance. Software sales have never scaled linearly with install base, this isn't a Wii-specific thing.

Wii's dropoff in 2011 is because Nintendo's first party studios moved on to 3DS and Wii U and as a result software support mostly disappeared two years before the system was replaced.

Smash Bros performed not much better on Wii than GameCube. I understand that sales don’t sale linearly, but if the numbers are this dissimilar between systems, this leads me to believe that it wasn’t the core “gamer” (i.e. non-gimmick crowd) that really drove sales, especially seeing the dip in Wii U hardware sales. Would you disagree?

I don't believe that customers really fall that neatly into diametrically opposed categories; you can be a hardcore Wii Sports player or you can casually play GTA or Zelda. "Gimmick" usually just means "feature I don't personally like". 

Please respond to my previous message but with the alteration: “Core” should be “purchased Wii more for Mario Galaxy, Smash Bros, TP, etc., and less for Wii Sports, Wii Fit, Wii Play, etc.” and “gimmicky/casual crowd”  should be the “purchased Wii less for Mario Galaxy, Smash Bros, TP, etc., and more for Wii Sports, Wii Fit, Wii Play, etc.”

Social gaming experiences like Wii Sports, Mario Kart Wii, and NSMBWii were the console's biggest draw; this wasn't the sole driver of its popularity though, as games like Twilight Princess and Mario Galaxy also played a role.

Why draw your conclusion from a single accomplishment? My argument is that Iwata didn’t manage the software pipeline all too well, and his handling of generational transitions was not good. He failed to keep Nintendo relevant during transition years, which is what led to Nintendo hitting such low lows during the Wii U. Wii was his only shining achievement, and even that is something I’d more attribute to Yamauchi who had set Iwata up with a plan going in: To decision to abandon power and enforce the Blue Ocean vision of Yokoi.

With all that’s gone on with the economy, it’s quite incredible that Nintendo has remainednas strong as it has— Furukawa has gone the trouble waters with flying colors in that regard. Under Iwata, we saw two poor console transitions that led Nintendo into dark times. And had Iwata been around for Switch, I question whether the system would’ve been as successful as it was. Launch year would have likely been more of the same from what we saw from the unimpressive (from the perspective of software) Wii/Wii U/3DS debut years— Wii was 100% carried by its innovative “fad” factor, a factor which didn’t translate into software successful for any non-Wii series titles (e.g. Star Fox and Metroid sold no better on Wii than they did on the much smaller install base GCN).

Iwata oversaw the software pipeline during the time when gamers felt abandoned by Nintendo. Iwata inherited a successful DS, wasn’t around to manage the entirety of the Switch debut, and fumbled the heavenly highs hit during the Wii/DS generation so terribly that we got Wii U and a 3DS was a massive price cut needing to save it. Iwata fumbled left and right, Furukawa has handled everything perfect.

Because that conclusion laid the groundwork for why the current leadership are doing well, Iwata's leadership came up with the Switch because supporting two separate platforms became impossible for the software pipeline. The current leadership didn't have to deal with the volatile situation of keeping two platforms going a feat that even Sony tapped out from, the switch consolidated the software pipeline into one platform with out abandoning either market, home and portable.

That's a leadership decision that still has Iwata ranked well above the current leadership as the long term implications are what have fuelled their success today, most other leaderships would have abandoning one of the markets to focus on the other.