1. Type Safety. TypeScript helps, but until strong typing is mandatory in the language, I can't fathom using JS in any sizable project. This is also true of Python, et al.
2. A sane dependency management framework. Maven solved this problem a decade ago. Gradle is trying to fix Maven's XML mistake. But the fact is, if I need a dependency in Java, I know how to get it. And as a bonus, Maven Central isn't going to go down next Tuesday because Timmy in Alberta threw a temper tantrum or something.
3. A sense of stability. Javascript's framework churn is just exhausting.