You're not wrong, that's for sure. We just lack imagination :D

I actually played Super Mario Kart more than any SNES game, and even after Mario Kart 64 blew up and kind of usurped its position as THE Mario Kart game, I still played the SNES version.

But yeah, the most long standing "definitive Mario Kart" games are probably Mario Kart 64 (1997 to 2008), Mario Kart Wii (from 2008 to 2017), and Mario Kart 8 - which will eventually surpass the original Mario Kart (1993 to 1997). So there's going to be a lot of nostalgia bias toward those games. I'm actually a little surprised MK8 is so low - but maybe most of us are older gamers now.

In Mario Circuit 3DS you can Drive through Peach's castle up the spiral staircase.

I have added this list of Possible DLC tracks to the OP.

In their current state the best tracks are mainly from DS and Wii, the SMK and SC tracks are lacking in quality. However you are right that SMK and SC have the most room for improvement, Ribbon Road and Cheese land proved this with their incredible MK8 versions. IMO Ribbon Road is one of the best tracks in the entire game, definately top 5.

3DS is too new for me to have Nostalgia. When MK started doing the classic tracks I just wanted Royal Raceway remade but was peeved they removed the ability to drive up to the door.