This forum isn't the only one I post on and the Galaxies are some of the most loved games on Wii (not that NSMBii isn't as well).
Out of the vast number of people who bought NSMBii, how many of them are willing to buy a $350 console to play a 2D Mario? Alot of them are more likely to pick up the console when it is cheaper. The 3D mario gamers on the other hand are likely to be early adopters, so there would be nothing wrong with having a 3D Mario at launch.
I'm not saying they will have a 3D Mario at launch, I don't care which we get or when. I'm just saying just because 2D Mario is the best selling one does not mean launch is the best time to release it. This console is likely to come out above mass market price.
I also doubt fans would crucify them for launching a 3D Mario.
I was not and am not limiting "forums" to just vgchartz. It is in no way true that the Galaxy games are the most talked about Wii games; not only have several other games outsold them (often by more than double), but you'd be hard pressed to find them even mentioned outside of the internet.
For your second point, you have nothing but conjecture to back that up and, in point of fact, I strongly doubt that you're right. That audience has proven to be both more rabid and more loyal than 3D Mario's fanbase, and I don't see how you can argue otherwise. They literally built Nintendo, and they're much more massive: not catering to them right out of the gate is sheer idiocy. Again, Montana vs. McNabb.
Finally, you're right that they won't crucify Nintendo for that. They just won't buy the system in as many numbers. And I want to point out that while we're focusing this discussion on just Mario platformers, we're only doing so in order to get a convenient example to wrap our discussion around: the bigger issue many of us have is with the direction Nintendo has taken with the 3DS and seems to be taking with Cafe. The former fears have thus far proven to be justified, and I suspect the system will continue to be outpaced by the "third pillar" (something which IS shameful, and don't let the revisionists tell you otherwise) until and unless it changes its emphasis. The latter fears may prove groundless, since we haven't had any concrete details about Cafe yet, but judging from what Nintendo's been saying and doing recently I suspect Cafe may become another N64 or PS3. Time will tell.