Given the beginning shortage of decent timber back then, I can also imagine that the powers that were would have wanted to discourage the wanton destruction (in effect) of high-quality boards. (For a coffin, unless you're going to do way complicated glue-up, you need boards at least 10" wide by 1" nominal, and preferably clear because knotholes, well.) So at the cheapest you're talking something like 40 board-feet of clear pine (or oak, or whatever), which would otherwise be enough to make a couple of beds or dining tables, or a cabinet, or framing for a shed, or planking for a goodly chunk of a boat.