The number of legitimate uses seems to drop pretty dramatically when you talk about a system that is used in a zero trust situation and irreversible.

I think the block chain philosophy as far as crypto currency and use for legitimate business just doesn't go hand in hand like some folks thought it might. People really don't want to do business if there is zero trust, and centralized databases, and strong courts, are fine. Even when there aren't strong courts blockchain doesn't so much fill the gap as provide a risky solution... that involves a lot of illegal and undesirable behavior.