I'm suggesting a concept for future level designs: verticality.
Basically, it's the idea of actually going down in-game using stairs and possibly a new asset, Party Elevators. Working like Party Buttons, they make the players go down a few meters, to a lower part of the same level (meaning it doesn't travel through depths, this stays untouched).
The new level design should give players a better understanding of depth and the idea that as Knights, you're going down through Cradle. You should be able to see the lower parts of the level while progressing in the upper parts.
This would be cool, but unnecessary.
The game is actually flat. You will never see a path that goes underneath of another path, or a building, or a hidden area under the level that extends under the whole thing. To code this wouldn't add much to the game, because we would still be doing the same thing over and over.
But an elevator would still be cool.