I think people under estimate SSMB a little too much. I know plenty of people who want nothing to do with the 3DS version. The only reason Nintendo is releasing the 3DS version first is because they want to milk the franchise as much as possible and they know that a 3DS version would be next to useless if released around the same time as the Wii U.
Can you honestly tell me you'd buy the 3DS version over the Wii U if they came out on the same day? Assuming you own both consoles of course. I get the appeal of having it on handheld over home console but the idea of having it on a big screen TV in HD is way more attractive. Plenty of people will end up waiting for the Wii U version, some will get both and then some will get the 3DS version because of lack of patience.








