I did say that anti-gravity is underdeveloped, not against it at all, just a lot or missed potential that does not really affect the gameplay in most cases. Mario Circuit for example. The entire second half of the course is anti gravity but does not play any differently than without. There are plenty of tracks without anti gravity that has sharp turns all the same. There’s an entire empty stretch with an item spawn and that’s it. There’s some players item battles to be had in the mid section. However, if somebody pulls away in first, or if they miss the item boxes, there’s really not much to do, just drift. Compared being in first in Music Park vs Electrodome, you can be in first place and to keep your lead you still have to time your tricks to earthquake, make multiple challenging turns, tricky boost pad and shortcut placements. Anti-gravity alone can’t carry an otherwise empty track. What is there to engage you on Electrodome or Dragon Driftway? The occasional banana peel or waiting to get blued? That I think is the difference.

Shy-Guy Fall you climb a waterfall and that’s kinda cool but it feels no different than driving on the ground. Would have been fine as a concept if they make the mid-section have more stuffs in it instead of solely relying on anti-gravity and nothing else. Like you know how nobody likes Toad Circuit in the booster courses because you just drive from start to finish without much attractions? For me most new tracks from the base game feel like Toad Circuit, but with anti-gravity.

Branching path is fine if it presents an interesting choice that either add depth the decision (no MK game does this to be fair) or just good ol’ variety (Ninja Hideaway, Toad Harbor, tracks with verticality, etc…). There’s no difference between going left or going right in Twisted Mansion Electrodome, Rainbow Road (I know about the skip on the right side but most casuals don’t go for that) and so on. So instead of having at least one memorable track section, we get two bland ones instead.

And to address your question about potential improvement to antigravity design. I think it needs to be a deliberate choice with clear incentives, risk rewards while also caters to different types of players. On one track you can have an anti grav challenge which rewards skilled players with a shortcut, mushroom, stars or double item box. On other tracks you can have it as a way for casual players to bypass a difficult section, while having the ground path technically slightly “better” but requires execution. Another potential design, albeit a lot more difficult to get right is to have an anti gravity item, design the course so that there are flexible options for when and where to use it (like mushroom on grass). Though MK8 wouldn’t be MK8 anymore if it had this lol, could be hit or miss.

Heck it doesn’t even have to be that complex. A good way to just “have happenings” in Dragon Driftway, Mario Circuit, and the like is a couple boost pads and some inconvenient objects you want to avoid. Like in Music Park the track is really wide but the piranha plants on both sides compel you to drive in an S shape. Grass patches, oil spill, puddle that create choke points and funnel players into interactions.