Not to sound condescending, but outside of internet forums the Galaxy games are not the Wii games that "people talk most about."
It's not even close.
As to your last question, let me respond with a football analogy. Imagine your team has two QBs, Joe Montana and Donovan McNabb. If the season is just starting, why would you ever make McNabb your starter in lieu of Montana? You'd be crucified by the fans...
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.