Team Bloodlust uses it as a gold sink like how many other things like mailing items to alts and market fees. Pets cost around the same to change appearance also.
I agree that it should not cost anything to do but at least lower the cost to do it to like 5-10g. (maybe a sliding scale for weapons IE: raven 5g, aransu 10g and GC 15g)
They also need something to give premium members so that is why it only costs 1g for them.