It's funny that one can make the opposite point. As I wrote a couple of years ago [1], we're getting to a point where many sites actually have obfuscated source, as there's much more attention paid to perfromance optimisations. View Source is becoming a thing of the past, at least as far as high-scale production sites go.
While you can still inspect the DOM and so on, but it's not as accessible if the source isn't there. So in fact, open source code on GitHub and so on is the best hope for learning and reusing, but that puts JavaScript in the same basket as every other language.
One thing I do in my daily job for the current project is to automate form submissions on various websites. I deal with obfuscated Javascript all the time.
It's really not a problem. It's also quite amusing when I see "protections" in place, like my local Yellow Pages that encrypts phone numbers that get decrypted when shown by a local Javascript routine, done of course to prevent crawling.
Obfuscated code is not readable. However a smarter view-source can take care of that - imagine a view-source that worked like an IDE. It could beautify the source-code (I'm sure you can already find plugins for this) and once you figure out what a variable / method does, you can then automatically refactor the code, renaming that variable/method.
It takes a bit of engineering, but obfuscated Javascript is still high-level enough to be useful.
This makes it no different from most programming languages. De-obfuscated code still takes a ton of work when you've lost all variable names, comments, and formatting.
Except most client-side applications are distributed in binary form. Grokking obfuscated assembly language is an order of magnitude harder than doing the same thing with Javascript.
On the other hand, browsers already allow for reformatting minimized code, I'm fully expecting better renamings/un-minifyting later on (patterns-based).
While you can still inspect the DOM and so on, but it's not as accessible if the source isn't there. So in fact, open source code on GitHub and so on is the best hope for learning and reusing, but that puts JavaScript in the same basket as every other language.
1. http://ajaxian.com/archives/the-end-of-days-for-view-source