This has been discussed plenty of times and lots of solutions have been given. I personally like the one person's idea that had you sacrifice the item to add it to the log so that instead of SE needing to hold all of the item's data it just saves the appearance. A lot of these items can still be used to trade for seals and stuff so there is still value in obtaining it again. Right now with it being hoard or farm I think the majority are hoarding which is doing nothing to help SE on data storage.

FFXIV is a game designed with the idea that you will level all jobs on one character. Even if it was just all crafting/gathering jobs on a single character, we don't realistically have enough space to hold all of the equipment and materials.