Wait, what? This runs completely counter to my experience of Haskell. I use it whenever I can, and I’m pretty sure I’m not a PL researcher. Lots of other programmers write actual, real-world programs in Haskell as well. Much of the discussion I see in Haskell communities concerns areas such as performance, toolchains and libraries — areas which PL researches are famous for ignoring. I will admit that we often talk about GHC extensions and type theory and whatnot, but the discourse around those areas is not all that mathematical; it tends towards ‘how is this useful for writing programs?’. In other words, exactly like every other real-world programming language out there.
(That being said, maths is fun, and I regularly see people defining weird and wonderful abstractions. But this rarely gets in the way of writing programs. If anything, every now and then someone comes up with an abstraction which turns out to be incredibly useful in practice: lenses, free monads, applicativeṣ, HKTs…)