One important of Python and Perl is that most systems have them pre-installed anyway, usually because some included system administration require them. If I write a script with #!/usr/bin/python as the interpreter, I can be fairly certain that it work (though it got worse since Python 3).
I do agree that Haskell provides much nicer and safer abstractions. From a high-level, conduit is like UNIX pipes, but with typing.
>If I write a script with #!/usr/bin/python as the interpreter, I can be fairly certain that it work
No you can't. Only some (poorly though out) linux distros do that. Sane linux distros (back when those existed) and every other unix-like system in existence won't have a /usr/bin/python. This is why /usr/bin/env exists and is a posix standard.
Which is fine, because that is merely a small part of the point. Using better languages is "normal", and we already have a 20 year history of doing it with Perl, and a nearly twenty year history of doing it with Python, the larger point being, "anyone writing these scripts knows how the hash bang works". In my mind, adding to the complexity of a system by requiring Haskell and this library is counterproductive when the goal us to improve maintenance efficiency.
That makes absolutely no sense. You are complaining that a haskell library, written for people who use haskell, requires haskell. Python code requires python, perl code requires perl, ruby code requires ruby. So?
I do agree that Haskell provides much nicer and safer abstractions. From a high-level, conduit is like UNIX pipes, but with typing.