Indeed, if you merely want a better java, Kotlin is now the better choice (especially considering the superior tooling). But the limitation is that Kotlin tops out as a better java.

With Scala you can start out in better java territory and go from there to wherever you want. I personally don’t use any of the pure functional libraries, but I still greatly benefit from the strongly and strictly typed but flexible type system. In the 50k+ lines on my most recent project, I can count the number of bugs that escaped the type checker with one hand.