[cheriot]

I suspect some combination of

1) It's hard for a new language to get traction. Lower odds that a new startup! They see so many ruby and python shops adding Go to their stack and want to compete in that space. Kotlin's biggest market seems to be android devs and competing with Go puts them in the datacenter.

2) IDEA's IDEs have a better value proposition to devs working with statically typed languages. Appealing to current Java devs builds the Kotlin ecosystem, but appealing to dynamic language devs expands IDEA's customer base more.

[watwut]

IDEA is pretty awesome with JavaScript too. The best IDE I have seen even for dynamic languages.

[pjmlp]

Actually Netbeans is also quite good for JS, it is a pity it gets so little love.

[manojlds]

Visual Studio code is great for JS and TypeScript btw.