[watwut]

Only because IDEs in other languages are weak as hell. It is not directory structure/boilerplate. It is code completion, analysis, discovery and all other similar goodies. It is just so much slower to produce the same functionality as you are used to.

Even basic things - ability to see all callers, all available methods, warnings on bad constructs and yeah, templates for often needed sysouts ...

Refactoring. Oh just a simple thing, like simplest of all available refactorings, rename something with zero worries about forgetting some place or changing one more ... I missed this ability so much ...

[fiddlerwoaroof]

I can generally use macros in vim + vim integrations for things like ag or rg to do refactorings fairly easily: sure, it's not as automatic as Intellij, but it's not bad either.

Also, depending on the language, the tooling in Emacs can get all the other IDE features you are talking about: for haskell there's ghc-mod + intero, for common lisp there's slime, etc. if you install the appropriate plugins and then use something like Syntastic/Flycheck, you can have all the nice editing abilities of vim/emacs as well as most of the useful parts of an IDE's language support.