Because having to kill 500+ Scorpions for a few Fine Grits isn't what I'd call a fun time. This is an item for the Rouge class-change quest and they shouldn't be THAT hard to get.
So my suggestion is this: Up the spawns for regular monsters a little bit and loot required for class-change related quests. Hell, I got a Scorpion card before I even saw a Fine Grit drop. I have 133 Scorpion Tails and in that time I only got 1 Fine Grit.