In defense of Node (God, there's a phrase I never thought I'd find myself writing), it's also much newer than Java is. Given ten or fifteen years for people to work on them, the docs almost certainly would get better.

To be honest, the Java API documentation is pretty stellar. I am/was a Python developer, and I remember hearing the claim that Django has great documentation. I don't know if I'm spoiled by Java or what but if Django passes for "great" then I think Java's docs should pass for legendary.