The same can be said about Scala and Groovy. (Groovy brings in those generators via an annotation)
With ChromeOS and Fuchsia on the game as well, it remains to be seen who will win Google's internal OS wars.
So far Android seems to be the one taking them all, though.
Outside Android I don't really see a major benefit switching whole teams away from Java, Eclipse/Netbeans and rewriting/wrapping libraries to be idiomatic Kotlin and such.
- supports both dynamic and static typing - it works just as well for bash level scripting as it does for full application development. For example, you can use it exactly like an interpreted language (no compilation needed).
- seamless Java integration. I know many JVM languages say that, but Groovy actually makes it one of its core features. It has a lower impedance mismatch than any other JVM language I've tried (and I try them all).
- partly because of the dynamic typing, it is able to support the most concise, powerful options in its syntax of any of the JVM languages. So you get more done with fewer, simpler lines of code
- because of the static typing and low impedance mismatch with Java, it can achieve very high performance. I was not able to get Scala to perform as well, for example, because of type conversions needed to invoke underlying Java library calls (unless you abandon idiomatic Scala).
- The amazing SQL library - HTML builders (there are XML builders too) - Literal collections (lists and maps)
This causes the program to run in dynamically-typed mode, much sloooower, so why do it? You'd have to add @Static annotations everywhere to get anything approaching Java-like speeds. One of the Apache Groovy project managers has long since wanted to make Groovy statically compiled by default, but that's never going to happen because they're running an unofficial go-as-slow-as-possible in the official upcoming upgrade to Groovy 3.