Ubiquity should not be an excuse for the promotion of what is, by all objective measures, a rather poor programming language.

This is especially true when it's an environment where there are numerous other languages available, and they're all so much better than JavaScript. Lua, Python, Perl, Ruby and even Tcl would all be better choices.

It's mildly excusable when it comes to web browsers, because JavaScript really is the only viable option. But that just isn't the case with a full-featured environment like OS X.