We've been steadily working on improving the docs, and rolling out significantly improvements on a regular basis. Is there any particular part of the docs that still ails you?
> the development of important features stalled for AngularJS as the team was busy working on Dart version.
Not true. Google grew the team. Take a look at the activity on Github. The velocity has been consistently high throughout the development of the Dart fork: https://github.com/angular/angular.js/pulse
If there was some important feature you wanted, you are always able to submit a PR yourself. That's how open source works.
Did they lint or unit test their code? Without having a way to verify that parts of your app work at a smaller level, of course it's going to get hairy when it starts to grow. Although a compile step verifies types, unit tests do that plus check against runtime errors. This is not a language problem.