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.
If you look at Java for instance, generics were made by one of the Haskell creators, and it has been implementing functional features for years now.