Exploration could have those sands and then those people who horded to make a quick buck might find themselves with less money.
The sands are not favor mats, they're aetherial node stuff. Any lv 60 gatherer can go to a node and get some provided they have a decent collectable rotation and luck. There's nodes almost around the clock. The market change seems to me like just a "pre-disaster people empty supermarket with no disaster in sight", since I don't see why sands would somehow have way higher demand. People using the sands are still the same crafters.