Javascript isn't the only language you can develop web applications on, in the same sense that assembly isn't the only language you can develop server software on. Javascript is what all browsers natively speak, and if you want your language to be understood by a browser, you must compile it down to javascript. The same can be said about assembly: it's the language that all CPUs speak, and if you want your application to be understood by a CPU, you must compile it down to ASM. In this way, you can see javascript as the bytecode of the internet.

So this shouldn't be seen as something negative: it's great, actually, that javascript is evolving in this way. It will allow for more flexibility: you can write your server software in clojurescript, your client software in coffeescript, and still share some common libraries for functions you need to call on both client and server.