I tossed out all my old mats that were rarely used to make more space for the new mats in 3.0, including all my Ureanus skin/leather, which was selling for 10-50 gil each. I had to pay 50k to get enough to make myself a skirt when 3.2 dropped and they were suddenly useful again. Very irritating. I have a feeling this is something that will keep happening too.