It is, I think, going to be very difficult to enjoy writing code in a less powerful language when you are exposed to languages that hold awesome power.

In fact, this has been the basis for much writing on Lisp too. Paul Graham has written entire essays along the same lines.

If you work in a job that forces the use of a less powerful language than what you've been exposed to, you can, I think, go through a sort of depression. You simply long to use the tools that you know hold much more power yet must resign yourself to the tools you have.

You can overcome the problem by being present in your work. The language might be ugly. It might be totally underpowered with limited means of abstraction and a type system that snmacks you and, sometimes, your client over the head. What you can do is, despite that, commit to writing great software with the tools you have. Commit to improving your work. Perhaps expand the ecosystem with tools borne of insights from your adventures with high-powered tools.

You will have a much more enjoyable time in most languages this way. Perhaps except MUMPS but there might be hope.

I don't know how to ask this without it sounding offensive, and I don't intend it that way. But do these "hardcore" haskellers enjoy writing programs at all? Like are there any well known open source apps that people actually use written in Haskell? There are tons of hobbiests and it has a following but what are the examples of its greatness?

I ask as an old SML guy, I like the math theory, I like the promise of better, more accurate and reliable software, I think you can do some beautiful things with algebraic types but I've been dumbfounded by the lack of great examples out there. Ada suffered/suffers the same fate, it has this "academic" pedigree for robustness but not many examples that you can get your hands on. so much expressiveness that doesn't seem to result in much expression.

Off the top of my head, Pandoc, a tool for converting between different markup/down flavors, and xmonad, a tiling window manager for linux. Both are well known and popular.

Is there anything actually interesting about what they do, though? Converting markup is not a complex task.

Parsing is something that's very pleasant in Haskell. Other languages can use parser combinators too, of course. It's good at it though.