Or you know, all the other updates the games actually had. You know, the ones that almost doubled the content of the games?
I addressed this in my previous post, I
know we've gotten content. What we haven't gotten is underlying framework changes.
Checkpoints necessitate a framework change, they're not like adding in a new enemy. Now people have to pass two checks to upload their level, one from the checkpoint as small Mario to make sure it's not impossible. Or Nintendo has to add in new options to let people start over from the beginning of the level, but then do they want to penalize people a life for that like they do now, because then you're losing 2 lives every time you cross a checkpoint and fail instead of just 1. It's not content, it's an issue of design.
Changing sharing options isn't content either, it's a factor of how they designed their level storage servers. Maybe they can't or won't store level tags. Maybe they have some terrible policy reasons why they're doing things the way they're doing, kid friendly like the rest of their design.
It's incredibly unlikely that we would see these features added, because they're less content and more core functionality, which Nintendo has a history of reluctance in updating. Even slopes are a whole new physics ballgame for all the different objects that can interact with each other.
Expect Chargin' Chucks before any of the above.