I don’t mind Kotlin itself so much, but the Java baggage it brings and the general weirdness that is possible when developing for Android in Java/Kotlin can get irritating. If not Rust, it’d be nice to be able to instead write Swift or some other modern compiled language suitable for UI work.
This is actually an area where iOS is more flexible. Because UIKit is C-accessible, it’s feasible to develop bindings to it for other languages, and even autogenerate them. It’s too bad the same isn’t true of Android Framework.