If we assume a stable system, not connected to any network, and fully backed up, what damage can cutting the power do?
Obviously it's a hassle to restore an image of the card, but a fairly minor hassle. Could the card be bricked (buying a new card is a minor expense but a more significant hassle)? Could the Pi itself be damaged?
I'm going to be building a Pi+touchscreen into a piece of equipment, which will have a swicth that can cut all power, and I don't trust my users (starting with myself).