The gem industry would be fine without nintendo obviously, but their franchises would be missed.

I'm going to emphasize this, as it's the first basic element to take into account when discussing the genre. Sports games existed way before Madden or FIFA, and they have always being a popular genre in videogames, practically growing with them. And as osed125 stated here, the reason is obviously because of being already popular outside of gaming, not to mention being already "games" by themselves.

http://en.wikipedia.org/wiki/Sports_video_game

Now, what makes Wii Sports relevant within it is how it brought back the arcade side of them to the mainstream through motion controls, while at the same time proving the potential of said controls. The genre had largely being trending towards the realistic/simulation side through the advance of technology, yet not everyone out there is interested in that. A part of the potential market was being ignored, and Nintendo took advantage of it while introducing new technology capable of expanding said experience. A simple, pick up and play game that could be accessible to more people from the start and focused on pure gameplay rather than simulate real events. So, while I wouldn't say that it popularized the genre, it did clearly reignite it. It was a shot in the arm needed for such an old and stagnant (in my opinion at least) genre that had a major impact on the entire industry, easily evidenced by how many followed it on Wii and other platforms.

Also, let's not forget that Nintendo had already made sports games even before the NES, and that on the NES itself they found a lot of success in the genre. In a way, Wii Sports was a return to those roots.

Oh, I wouldn't mind seeing Platinum's take on Star Fox at all... Although, if Nintendo is going to outsource it, Treasure would be my first choice. I believe they're the most qualified for the work, with their extensive history on pretty much any kind of arcade-style shooter.

Obviously Nintendo and their games are important. Obviously systems other than Nintendo are important.

Hardcore Nintendo fans who refuse to try other systems (I was one until 2010) seem to think the other systems are worthless.

Hardcore Sony and/or MS fans who don't 'get' Nintendo don't feel disposed to give them any sort of credit, either.

I believe the vast majority of gamers appreciate all the companies for what they are, and find this sort of argument kind of pointless.

Treasure made Sin & Punishment: Star Successor, and I thought that game was pretty bland. Platinum games has made a lot of amazing action games, I think they would "spice up" the Starfox formula well.

More importantly, treausre made Ikaruga.
The best shoot em up there is.

Lol, "dead". Check the latest chart, you'll find both Just Dance and Wii Party U in the global top 16.

Wiiu party is selling ok at best, and I'm doubting just dance will be around forever. Two games doesn't really sound like a thriving genre to me.  

360 post-2010 still offered just about all the same games PS3 did, and equivalents like Halo 4, Forza 4 & Horizon.

And Wii Sports popularized motion-based games. 

Wii Party U will be over a million by now even on a small install base, and with MS pushing Kinect with every Xbone, motion isn't going anywhere.

Yea, but Starfox is not a Top Down shooter, the only rail shooter experience they have is Sin & Punishment. Treasure also made a lot of forgettable games, like Silpheed for PS2, and Astro Boy....

They don't have a guarenteed track record like Retro Studios or Platinum Games has (but to be fair PG made Anarchy Reigns, which was their 1 bland game)