I explicitly support Brendan's arguments. Programming languages are a STANDARD to help people COMMUNICATE units of functionality. If we frequently invent new languages that just mainly give us a new "style" to do things (and of course some will do this better, and others will do that better), we get an unnecessary chaos of different codebases that will be incompatible to each other but yet do basically the same. (1)
Language design implies even more responsibility in versioning and adaptation to new programming paradigms than API design.
It doesn't matter that much in which language a program is written, as long as the language level fits the level of your module / application and portabiliy (1) is high.
I would even vote against a separate module type and other experiments that complicate JS sytax. But this is, of course, another discussion. What I like and heavily use is CoffeeScript.
Thank you Brandon for keeping things in order!