That might eliminate the concurrency imperative (for a while!), but it doesn't adress the productivity point. My hypothesis is this: People don't like using unproductive tools, and if they don't have to, they won't.
productivity is not the only metric for a tool for some people, it is performance for many employers, it is access to a vibrant labor pool for some other coders (database admins, web developers), they don't even have a choice of tool and how do we measure productivity? i would claim the tool that requires me to produce the least new code to get to a sufficient solution is the most productive. haskell's syntax and semantics can aid in reducing code, but do not address real problem domains. thats where hackage comes in. compare hackage to cpan, we've got a ways to go. i'm going to add something to hackage tonight to help!