[the_af]

That's only partially true. Of course a Haskell program needs to do IO to be useful. The IO Monad is also not a deterrent, where did you get that idea? Haskell is very much IO focused, in fact it's been jokingly called "the world's best imperative language"!

Even then, in Haskell you can say "this doesn't do IO" which you cannot in most languages!

It's also just an example of the expressiveness of the type system, which "most statically typed" cannot enforce or sometimes even express.