It would be really cool to see the user-friendly version (though that might lead to a rabbit hole on the Closure side, too). The Closure compiler remains awesome, just difficult to make use of successfully.
You might try out https://github.com/theseanl/tscc , which aims to do this.
It's a bit difficult to hook up though, and we haven't had the cycles to make the open source version user friendly, I'm afraid :-(