I do not really think it is hoarding to play the game as intended. With the huge amounts of item bloat for crafting, all classes on one char, different tokens and currency, it is more like general stuff to play the game. Hoarding would be having stacks and stacks of bone chips that you want to keep. Wanting to keep my hard-earned dreadwyrm gear, crafting supplies, etc, is not really hoarding. They devs even stated that there is an inventory shortage and they know about it.

But that aside, that is the point, since they /do not/ purge your items when the retainer expires, the stuff is still there and taking server storage just arbitrarily letting you not use it since you did not pay that month again.