Just a few players are actually training fletching, as it is a pretty useless skill. It's not easy to sell if you have lots of bowstrings. Just placed an offer for 10k bowstrings at 3.5k each, and I recieved them immediately.
You were stating that it was a money making method for many people, and now you're saying only few people buy them. Because of the higher price there might be a more supply than demand. If the prices were dropped, the demand would get higher, and more people would be thinking about training fletching.
Win-win if you ask me.
It's a money making method because you gain a lot of money quickly and without any requirements. The amount of bowstrings needed for one player is not met by one supplier, therefor it is a good money making method for a lot of people. Example; when I got 200m fletching xp it took around 15 different players to supply me with all of the bowstrings or flax.
OT: I think this would be a cool idea because it might make bowstrings/flax a little cheaper and easier to get for yourself.