It's all relative I think. Depends on time period and area. The surviving early guns seem to have pretty much all had them but you do see them with out from time to time. The later in time you go the more elaborate they get and also at the same time you start seeing them less on "economy" models.
My own personal feeling? Put one on if you want and don't if you don't want to. But, if you don't put one on you should probably scale back the other carving and engraving as well. I never use them much, but they are a great place for decoration.
It's possible the "economy" models in all time periods that didn't have patch boxes got used up, there may have been more non PB guns than we imagine. Or maybe not.....