let's not keep relying on the forum software to do all the work, the more transactions it makes the more bandwidth it takes. while yes, a jpg is worth about a thousand text but remember that the server also transacts with the other members, which also take up bandwidth. while the server is resizing your hotlinked image, it is taking some bandwith from the other users as well. multiply this at least a hundred times...well, you get the idea.
to give you an idea how much this site takes up bandwith, for this month alone, it has taken up 19 million hits from around the world. and take note, that is only for the month of May.