And this is something I was unaware of until now, a "Contributor License Agreement"[1] is required for a pull-request to be accepted. Sheesh, that's kind of a PITA...
At the last London AngularJS meetup it was mentioned that the team have 'pull request parties' where they try to merge or close as many contributions as they can, but more of them just keep coming ... good problem to have I guess, but they are aware of it and trying to address it.
It's one of those nasty problems, like the influence of money on politics, or gerrymandering, where the people best able to fix it are the ones least likely to think it's a problem.
The current docs have come a long way from their previous state - I recommend people try taking a look at them now. The developer guide & API docs have gotten huge improvements within the past month! I think the only things that are really left is to recommend some best practices with examples and more examples in the API section.