Basically, I'd love to have what Guild Wars 2 has currently by way of the "Collectables" banking system. Essentially, crafting materials take a pre-defined slot broken up by categories. You can move any crafting material from your inventory into your "Collectables" by right-clicking it and saying "Send to Collectables" (or something like that).

Maybe make it a craftable item and have it sit in FC housing, and personal housing if that ever happens. For value adds, you could then make it filterable/searchable and sortable. Not sure whether they'd want to go so far as to

This would leave Retainers for sellable goods and weapons/gear, and it would help people who like to craft from filling their entire inventory/retainers/bank with random crafting materials because they might need them some day (like say, me)