I wondered the same, but it really, for me anyway, came down to convenience.
I am not that technical so I don't do much more than the batch operations of backing up, verifying my backups and restoring apps after loading a new rom. With the pro version I am able to do my restore with basically the one click to kicking off the batch run rather than having to agree to installing each app individually.
I am sure there are others out there that can answer to the more advanced options