Arne said the other day that he talked to a few fellow NDs and they seemed surprised that it wasn't in the game, and as has been pointed out it was present in the launch trailer and seemingly present in the particular build ND have around the office (hence why ND were initially insistent that motion blur was in fact implemented in the game). If the effect was removed intentionally, we would have confirmation of that by now.
Edit: I am well learned in the functions of game patches, however what you don't seem to understand is that motion blur was present in the game prior to release and apparently removed erroneously, thus the effect is already supported in the engine; that is to say, there's no need to implement the required code for the effect as it is already present and just not being actively parsed. Obviously, as you suggest, in cases where post-processing effects were removed with reason, it is unreasonable to expect them to return by way of an update.
