Link gives credit to where I first saw this question.
Maybe they're saving that name for when they actually make another game that uses the same formula as Super Mario Bros. 2. (The international Super Mario Bros. 2, I should say. I don't know what they'd call it in Japan.)
The core Mario titles usually don't have numbers. Spinoffs and remakes are another story, but the core titles dropped them a while ago. Super Mario Bros. 4 is Super Mario World, but that makes Super Mario World 2: Yoshi's Island into Super Mario Bros. 5, and that would get really confusing if it was allowed to continue, so Nintendo basically gave up with the numbers. Super Mario Galaxy 2 is an anomaly, but it's also the first Mario game released on the same console as its predecessor since the NES.
How are characters that aren't Mini able to get into the Mini Pipes along with those that are?
