Many of those tools (including Coco, a CoffeeScript fork which is, objectively, more feature-rich) provide features to help manage asynchronous control flow (that is, to make callbacks look more like linear code). These proposals were rejected in CoffeeScript (see https://github.com/jashkenas/coffee-script/issues/350) because they take the language too far away from the underlying JavaScript—in particular, CoffeeScript code would no longer necessarily have the same order as the JavaScript output.

For heavily async code, those other tools are well worth looking at.

We use Parenscript heavily. It's great. The full power of Lisp macros on top of efficient JS.