It seems to me that, despite being one of the world's most used languages, even some of the leading experts of JavaScript like Doug Crockford think JavaScript suffers from some pretty big design flaws (JavaScript: The World's Most Misunderstood Programming Language) that make development confusing and ambigious.
Programming languages and development tools are always getting better and make it much easier for developers to make things. There's a new version of .NET every few years, new version of HTML5 with new tags, new versions of CSS, etc.
Why hasn't there been a better version of JavaScript or another dynamic loosely typed language, but without all the design flaws, come out to supercede JavaScript?