There's a lot of variants to that rule, but I agree... they needed to change more to avoid all the flack the game is getting.
But some things to consider (all for japan, but can be applied cautiously to other regions too)
1 - First: 3DS is not the DS or the Wii, nor it's going to be. They were disruptors, 3DS isn't
2 - The DS and Wii games were, respectively, the first new 2D Mario in 15 years and the first console 2D Mario in almost 20.
3 - NSMB Wii was the star of 2009's Wii christmas - not an august release. 2009 was THE year for Wii, I think
4 - There were 2 million more DSs and 3 million more Wiis when NSMB and NSMBWii released than 3DSs
5 - Competition from other games is this time is MUCH bigger. Seriously, third party support from both 2006 DS and 2009 Wii was redonkulously bad. Now take a look at 3DS games.







