I've watched these precompilers come and (perhaps) go. Granted, I'm a big fan of the likes of SASS, LESS, and tools built on those platforms such as Autoprefixer, as those give me new tools (mixins, variables, modularization, automatic vendor prefixes) I don't have in the "native" language they compile into.

HAML and Coffeescript only change the syntax.

To me, this adds little value. If Javascript appears scary, spend more time with Javascript so groking it becomes easier for your brain. Making a tangental change to a completely different syntax seems like a wasted investment. When debugging in the browser, you're still going to require knowledge of JS, even with source mapping. Delving into other libraries will still require knowledge of JS. The entire JS community is not hardened in Coffeescript, so the pivot you make to learning Coffeescript is time not spent learning JS, setting you behind when groking other source.

HAML seems to add even less. HTML is just markup, it can only ever get so scary, and if you're in control of the source, you should strive to not make it scary. HAML seems like the worse case scenario for hand-holding.

That is to say, I'm not against precompilers that actually add something useful. I'm in the middle of evaluating TypeScript, and depending on its 1.0 release and its community support, I may very well choose to fully adopt it. But for me to start using your precompilation tool, you better be adding more than just syntactical changes. If you're worried about needing tools to help you remember to close an HTML tag, your problem isn't with the language, you just need to become a better programmer.