The FP Open OS is available since a couple of months. It is rooted by default.
And no, I can’t recall any official statement from Fairphone before the FP2 launch that said it would come rooted. Please show it, if you know where it is, I was looking for it when I received my Fairphone, because I was super pissed that it wasn’t rooted and I also thought it would be.
In any case, with a delay of some months Fairphone published a rooted version of the Fairphone OS, additionally also free of GMS. If you’d like to install it, here are the instructions:
http://code.fairphone.com/projects/fp-osos/user/fairphone-open-source-os-installation-instructions.html