The ability to organize tiles painted within different layers could open opportunities for a lot of creativity and verticality! Such as having different layers represent different floors, so you can reveal the layers appropriate for the party to explore dynamically within a scene! Please consider this feature, as verticality is something very scarce in TTRPG and VTTs in general!
Also, I'm aware of the alternative of creating floors as different levels, but that's just not the same! For one, constantly switching between levels just to manage two different floors within a combat scene for example, is really tiring and not really viable. Think this through, imagine how cool vertical encounters can be! Players firing from scaffolding to scaffolding and such!