All great questions for us to ponder. I think it is a tikkun even if we can't see the reason. In fact, I once asked about how to do tikkunim for specific aveiros, and was told something along the lines of;

"Don't worry about specific tikkunim or sins, but just keep doing all/as many mitzvot as possible, so as not to miss anything. You'll make tikkunim this way."

So I guess in the same way suffering in general is a tikkun, this is too. You are right though, there is a chance for deeper teshuvah/corrections/connections with awareness and reflection though... Maybe it does relate to the finger itself, but as you imply, only he could know...