No reason. Some folks here think it’s part of a “guide” for CNC. But they also make models without the hole. And without pick guards altogether. And none of the Charvels made on the same tools have the hole. And no other brand of FSO has that hole.
You can put your weed in there.
You can put your weed in there.
But be warned, if you’re thinking of changing pickups, the bridge pup might be the same size as the neck pup. You’d either need two neck-sized pups or have a little routing done to widen the bridge spot.