The New Super Mario Bros. games are more like Super Mario World than something like the original Super Mario Bros. And they did what they could to make to character models 3D among other things for a fresh "new" feel (Hence why "new" is in the title). I think that Megaman 9 set itself apart from all this and was a love letter to fans. It had the 8-bit graphics, the catchy music, almost the exact same gameplay from the 80s, and the same blistering difficulty. There was even the feature to turn the flickering graphics on or off. What I'm saying is New Super Mario Bros. didn't have the same presentation Megaman 9 did to be consider as the same kind of "retro game revival".
It's called Retraux.