Send documents with unassigned fields
to be able to send the document even with unassigned fields.
Bassem Naguib commented
1) Variables are not good for checkboxes
2) There is often an optional secondary signer. So the secondary signer fields may not be assigned to anybody.
3) For backward compatibility. A lot of the classic editor templates made use of unassigned fields. So allowing them on the v2 editor will make the migration much easier.