The thing is, this is almost identical to well written JavaScript. In fact you could do almost all of this in JS even before ES5. So the non-Java-like features you're using here were already present, which again suggests that Dart isn't really getting past the "Good Enough" problem.

It's also something you could do in Java, with the exception of having to wrap main with the obligatory EntryPoint class.

I think this just goes to show that good code can be written in almost any language (except Perl of course) because writing good code almost always just means writing obvious code, which necessitates avoiding cleverness and obscure features (literally all of Scala), twisting control flow (I'm looking at you State monads and call/cc), or adding too many indirections due to limitations of the language (Java).