Relative to what? Haskell and OCaml are important languages for PLT but not in the context of "production", or as I understood "production" to mean: shipping products with features. To call them anything but niche players in this context is not accurate in my opinion.
I know less about OCaml, but at least Jane Street is using it.
It's somewhat niche, but it's not like it's only used for hobby or toy applications.
[1] https://code.fb.com/security/fighting-spam-with-haskell/
There's a lot of OCaml in the program verification space: https://frama-c.com http://why3.lri.fr https://alt-ergo.ocamlpro.com
And for mysterious reasons, OCaml is now kinda popular for.. web frontends. Bloomberg created an OCaml-to-JS compiler https://bucklescript.github.io and Facebook (again!) created an alternative syntax https://reasonml.github.io and this combination is apparently a new hipster way of writing web apps.