They have been made considerably more rare Oak, and grinding them is also very slow if not impossible. I'm guessing that was to help the economy with some rares. As for Raven Moon we seem to get more Masonry BP's out in our area (696), though still quite rare.
I have found at least one type in almost every area pile. full set of mason in one day south of oasis, a few tents and such to the west of there. some areas i seem to get a few in a day others i might get one. As far as my personal experience at max skill and over 120 charm and per the mist areas didn't pay out any more then some of the others