I believe that in the coming years we'll see some people realizing how good the Wii library actually is. When Wii's weaknesses are no longer important and the Wii U starts having its droughts of first-party releases, I bet there will be people who will finally wake up to the great games found on Wii. Just like it happened with the Gamecube during the Wii years.
Nintendo Power compiled a good list. Of course I don't agree with all choices and placements, but that's expected. Galaxy 2, Silent Hill, NSMBW and Sin & Punishment would all be higher on my list.
Dead Space Extraction is okay but it misses one important aspect of arcade shooters: replayablity. All that story non-sense is okay for the first time, but really bad when replaying it. I don't think this game deserves to be listed as a should have.
Klonoa is another one which I don't see what's so special. I liked the game, but it was nothing more than okay. I don't have nostalgia for it, it was my first time playing it and it's fine. But it's not a should have. Again, the story and cutscenes drag it down.
My last gripe is that Madworld is such a boring game that I wouldn't even have it as even a nice to have. No More Heroes 1 would be much preferred.
Main omissions in the list for me: Fire Emblem Radiant Dawn, Muramasa, WarioWare Smooth Moves, Wario Land Shake It, Excite Truck, Bit.Trip Collection and Wii Sports Resort. Fire Emblem is second only to Brawl as the Wii game I've put the most hours on. And WarioWare is also a must have for me. Everyone I show that game to ends up loving it and I did get my cousin to buy her a Wii because of that game. It's really damn fun.
I'm glad Boom Blox didn't steal the spot from other games. I know that game is overall well-liked, but I see nothing that special in it. It's okay in multiplayer, but I'd much rather be playing NSMBW or Mario Party 9. That said, a much more undeserving game I see mentioned a lot is Deadly Creatures. It's just terrible and doesn't deserve recognition. That one and Madworld are the two main Wii games regrets I have.
This thread does remind me I still have some (supposedly) great Wii games for me to play in the future: Little King's Story (already started; I'm a couple of hours in), Rhythm Heaven Fever (also started), Red Steel 2, Xenoblade, The Last Story, Pandora's Tower and Trauma Team. I'm currently going through Kirby Return to Dreamland. Should focus on Little King's Story and Rhythm Heaven next.