It's perfect so you should never do it again? That's your logic? The graphics point was to do with the general treatment of the series.
Artistic mastery? That's nonsense. Just make fun games. We'll judge what was an artistic masterpiece in 50 years.
There have, of course, been far more 2D Marios than 3D, but almost all of them came out from 1985-1992. That period gave us SMB, SMB2, Lost Levels, SMB3, SMW, SML, and SML2. That's nearly annual, and it didn't kill the series.
Since 1992, there have been four 3D Mario games, with a fifth announced, and just two 3D Mario games. Despite it being by far the most popular games series of all time, the equivilant of three home console generations passed without a home console 2D Mario.
The right thing to do is roll them out every 2 or 3 years like they do with Zelda and 3D Mario. Two per system. And pump up the content. Introduce new boss enemies, new environments. Keep it up with the new powerups. Jack up the amount of levels to 100, then higher. They certainly haven't run the formula dry. One of the key ways they mixed up the formula for NSMBW was spinning platforms. That would have been possible on N64. Nintendo just wasn't interested.
And the other thing to do, is make sure the other 2D platformers released for the system get treated properly as well. That takes the pressure off 2D Mario to do annual games like Guitar Hero or Need for Speed. If DKC Returns had the tight controls and jump-in gameplay of NSMBW, and games like Wario Land and Kirby's Yarn took more straightforward approaches and stuck to the tenets of the series, and Sonic 4 wasn't some DLC misstep, then there is no need to overwork 2D Mario.
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.
