I don't really get this. Conceptually, haml IS html. Sure the syntax is a bit different, but it's hard for me to imagine that a decent programmer would get hung up on this. Same with coffeescript really. If a cleaner syntax on top of a language scares you, you don't really grok the original language all that well in my opinion. There are certainly arguments for sticking with vanilla html/js, like the potential minor hassles of dealing with file conversions and debugging generated code, etc., but fear of a new syntax that can be learned in 15 minutes is a weak one.

Edit: I do grant that js to coffeescript is a bit more of a leap than html to haml since coffeescript actually introduces some new language concepts.