Kotlin is simply a much more modern option than Java in general, and doubly so for the old version of Java used for Android. Giving Kotlin some official backing gives it a lot of credibility. The big argument favour of using Java over Kotlin until now has been that Kotlin was seen as more of a fringe language than the one (Java) officially endorsed by Google. Now that has changed. As a Scala developer I'm quite happy that Kotlin is getting this much attention as I see it as Scala-lite. I doubt there's a campaign of any sort, just lots of excited developers who are sick of Java and excited about Kotlin.