Personally, I work the same way you do. But I've heard enough people who want the faster feedback of a REPL-like environment to accept that their approach at least feels more productive to them. It may even be more productive - for them. If so, tying them down with type specifications would slow them down, at least in the prototyping phase.
That certainly seems like a reasonable hypothesis to explore and I'm curious to try a Haskell "EDN"-like type as defined in the article to see if that helps me prototype faster!
