And this is true for many more languages (Flow, PureScript, LiveScript, IcedCoffeeScript, ...) which don't innovate on many aspects but just offer a slightly different - sometimes improved - syntax. I do recognize that many languages add value, but that must be offset to the cost of using these languages. Costs which are often quite high: Googleability, StackOverflowability, documentation, tooling, develop mindshare, library support, stability - these things don't come cheap and take years to mature.
Furthermore, these "innovate slightly" languages in the webspace take away resources from improving the current state of the art in mainstream (EcmaScript, TypeScript, Dart, C#, Java, ...). For instance, instead of improving some JS tool now resources go into e.g. writing a language server for aforementioned language.
A good example is Elm which does try to innovate on core concepts (builtin reactivity). That's a conceptual feature which can bring the state of the art of programming language design further.
Last, I do not mean that we should not write any more new languages; but we should stop trying to get large-audience adoption for "innovate-slightly" languages. It's a waste of braincycles and actually hurts the ecosystem.