Why cancel at all if the trip did not happen?
Because the visa exists on a record attached to the sponsor, and an open entry there can complicate the next application. Sponsors who have quietly accumulated two or three unused visas often discover it at the least convenient moment.
Cancelling closes the file. It is administrative housekeeping that costs little and prevents an argument later.
- An unused visa remains recorded against the sponsor
- Open entries can complicate future applications
- Cancellation closes the record cleanly
- Cheaper and simpler than untangling it later