For thematic tournaments that do not start from the initial setup (e.g. King's Gambit Tournament), it would be useful to automatically generate a PGN that starts from the beginning.
For example, the King's gambit tournament in theory skips ahead past moves 1.e4 e5 2. f4 exf4, but then on the PGN that you might use to export it may start out with move 3 as if it were the first move (e.g. 1.e5). Since these games are more or less "complete games", it would be nice to export them as complete games without a lot of manual steps.
In theory, this would only require the PGN to include the "omitted" moves, although as a programmer I realize you must deal with other games that truly are setup from an arbitrary position in which automatically inserting moves may not be possible.