It’s true that writing SPAs in general is more complicated than writing, say, a traditional, server-side web application. Regardless of the language. JavaScript and its tooling just makes it that much more complicated. The Angular model, for example, is quite difficult; easy to get started, but you run into trouble quickly when your application grows. Using a transpiled language like Amber or Dart or Scala.js avoids the Angular complications; you write your application in a fashion similar to most other kinds of applications, i.e., a simpler fashion (none of this two-way data binding and dependency injection crap). (Disclosure: I use Amber Smalltalk.)

A “fixed” version of JavaScript won’t address this issue, of course. The problem is still in the JS frameworks. But at least it’ll make JavaScript more palatable on the server side, as well as in other areas like the Internet of Things.