Don't forget that MK:DD was disliked quite vigorously by a decent sized section of the community.

It was on purpose :)

"SSBB- The cube version sold 6.6 million on just 23 million consoles.... Imagine what it can do on a userbase the size of the Wii's. I personally believe 20mil LTD. is not out of reach (it would be the first non-pokemon, non- bundled game to do so)"

Kids.... dont do drugs.

Reasons why Nintendomination is still on an upwards trajectory:

1. SSBB and MKWii + Online = Teh Win.
2. Still no WiiDogs announced. Does anyone doubt that will be a huge release?
3. Most 2007 3rd party titles were second rate, rushed affairs. Zack and Wiki, Trauma Center 2, and MOH2 proved that given time third parties can figure out the WiiMote and make decent (and varied) titles for the Wii. With most developers coming around to the Wii only in early-mid 2007, we have every reason to believe their best efforts will be landing in late 2008-2009.
4. Mario + Sonic = $$$$. These two have only just begun.
5. Neither the 360 nor the PS3 currently seems able to get past the other. There is a good chance that the two will stay deadlocked for the next 1-3 years, which will allow the Wii to continue to move higher.
6. Many Nintendo franchises remain untapped - Donkey Kong, FZero, Luigi, Icarus, Mario Sports, etc.
7. We had Zelda, Metroid, Mario all in Year One. Does anyone think these won't have some sequels? (and don't forget WiiSports 2)
8. What? Still no DS connectivity? You know that's coming, and Nintendo can use the DS's rediculous success to shore up Wii support.
9. Nintendo remains the only one of the 3 current gen systems to not have a price drop. IT also is the only one that never needed one, despite the fact that they could have shaved $50 off the price without going into the red. The second that Wii supply exceeds Wii demand, expect a flood of new Wii colors, along with a price drop that'll make the competition weep.
10. The X Factor - nothing breeds success like success. As with the PS1 and PS2, Nintendo's early lead will result in a positive feedback loop as players attract developers that attract still more players.

Why?

Games sales don't go up equally with the install base.

System Sellers usually don't apply when it comes to install base. If it's a system seller/flagship, that means people will play the game at any cost. (that's why they're called system sellers) So most people who wanted to buy the game did. Will the total sales be higher then its GC counterpart? Likely, but not by a lot. Just look at Halo 3, it will probably outsell Halo 2, but only be 1.5 - 2 million. (despite the eventual much larger install base)

Games that benefit from install base are the Tier 2 games, or complimentary games. A game where most people won't buy the system to play it, but will definitely buy it/try it if they ever do get the system.

I think a game like Ratchet and Clank falls into this category. (as an example)

Also, think of who is buying the Wii. It has its hardcore install base they've always had, plus the people who have reverted/gone over to their side. But how much of the rest of the install base is a casual gamer and not interested in Mario Kart/Smash Bros? 

However, only time will tell

 You had a good post going until this last paragraph here. Mario Kart and Smash Bros have more casual appeal than any other title in their genre. That's how most blockbusters achieve blockbuster status.  Halo wouldn't move the millions of units it does if casual gamers didn't find it to be a very approachable shooter. Same goes for GTA, where a lot of casual gamers don't even bother doing missions, they just hijack a car and have a blast causing mayhem.

 Wii sales of these franchises may not stomp their GC predecessors into the ground, but a casual userbase isn't going to hold them back in any way.