Haskell is useful whatever your priorities are (unless you have a really low quality requirement, like a script that fits on a single page and gets run only once). If you think of the project management triangle, switching to Haskell gets you a bonus that you can distribute between the points as you wish: you can produce higher-quality code for the same scope/cost/time, wider-scoped code at the same quality/cost/time, code at the same quality/scope/cost in less time, or so on.
IME a lot of Haskell advocates spend this windfall in a way that's poorly aligned to business requirements: we spend it all on increasing the code quality (and perhaps even overshoot, taking more time than users of another language to produce code of the same scope). But that's not an inevitability. (I would speculate that it tends to happen because most people in the software industry claim to value quality a lot more than they actually do, and a lot of Haskell programmers take them at their word).
IME a lot of Haskell advocates spend this windfall in a way that's poorly aligned to business requirements: we spend it all on increasing the code quality (and perhaps even overshoot, taking more time than users of another language to produce code of the same scope). But that's not an inevitability. (I would speculate that it tends to happen because most people in the software industry claim to value quality a lot more than they actually do, and a lot of Haskell programmers take them at their word).