Other than a rather dated syntax there is nothing 'depressing' about the ML family. After you write something like MirageOS in Idris or Agda come back and report on the experience 🙃
“depressing” is an overstatement, but the fact that you can't, say, write a list indexing function without the possibility on every call of it failing makes me sad. (Oh, and Hasochism, or its OCaml equivalent, is actually depressing, so don't suggest that.)
Dependently typed langs can be disappointing when you learn that you have to duplicate your definitions a bunch and erasure/phase/staging is really hard! 😂