> Some of the new features of ES6 - Symbols, proxies, Object.observe, et cetera - seem to make it downright easier to write even more confusing code.

Actually, they're things that actual users of javascript have been asking for (and implementing hacked-up solutions for) for a long time. There's a reason Coffeescript is often referred to as "a better javascript" and Typescript is considered its own thing.

Javascript is a dynamic language, and will never make the transition to a static one. Its users don't want a static language - the people who want a static language are using things like TypeScript.