[seddona]

I think this is an important point actually.

Programming languages (at least in the context being discussed) are just a means to model a problem domain. Some people find it easier to model domains in strongly typed functional languages but at a much larger percentage do not. Let's for argument's sake say it's 1% of all programmers. That is still a huge number of people though.

[galaxyLogic]

It could be argued that coming up with the original model was easier done in Haskell by the expert Haskell developers. Translating it to another language is more or less mechanical task. Then the maintenance and further development can happen in a more commonly known language.

In other words languages like Haskell, Lisp etc. are precisely good for modeling the problem and its solution, so it can make sense to use them for that even if later development is best done translated into a simpler-to-use language.