I have done the worm hunting with the rake during a rainstorm ... and there aren't many worms for me (temperate zone). Just two after many spots digging. So maybe up the number a bit?
But here's my more important issue: the rake does make holes or lowered terrain with raking, and it's kind of annoying when you don't really want the lowering to occur. Perhaps we could have a different tool for digging worms, or and different setting or key command for raking without changing the ground depth? I know I can go back and raise it, but I'd rather not have to. For now, I guess a pit outside town will need to be my worm farm!