Storage wouldn't be so much of an issue if items from past xpacs were made largely irrelevant, but they sadly aren't.
The new goldsmithing metals require a number of ores from ARR (including copper ore), ALCs need mats from HW for SB recipes, and don't even get me STARTED on what CUL players have to suffer through.
I can appreciate that they make older gatherables valuable in this fashion, meaning that someone leveling botany can gather HW mats that are used for level 65 reisuis in ALC, but at the same time, this whole situation necessitates more storage.
Otherwise, you're going to find yourself constantly selling and rebuying/harvesting mats you NEED for your 65+ recipes.