How not to handle open source contributions
github.com
github.com
All the reasons you ascribe to it aside from "documented" aren't applicable here. The feature was in the bigger vision, it was well tested, backward compatible, etc...
The only reason touted for not accepting it is that they wanted to get another feature in first.
I think it's really the worst way you can handle open source contributions, and it actually typical of the angular team behavior.