Why not haskell?

Inspired by the various replies to the "haskell for non-haskell sake" I wonder why so much people uses haskell "only for prototipying" or producing code in other languages. I am just curios to hear from people who do not use haskell for project releases, or just think it's not suitable for a mature project, what exactly they find bad in current haskell implementations, or perhaps in the standard. Vincenzo