I did say earlier that I find this Mario Kart roster to be worse than anything that's going to happen in Smash. Not only are there no big newcomers outside of the Koopalings, but a handful of veterans who should be obvious inclusions for a console Mario Kart missed the cut as well. We're not losing major secondary characters like Wario, Diddy, or Dedede just yet (although if we somehow did, the Smash fanbase would probably defend that as well with "At least we have XYZ characters and the game looks great, so stop complaining!").
In comparing the two, I'm hoping to demonstrate a principle shared between the two franchises; sometimes their rosters are less than satisfactory, and when they are, criticism is kosher. Mario Kart's roster was a hyperbolic basis for comparison that happened to fall into my lap today.