Why put your packaging needs into game-data-packager?1. game-data-packager (gdp) runs as a normal user. postinst scripts run as root. This reduces the impact of a security flaw in the scripts.2. the .deb packages that gdp generates can be archived by the end user and installed on multiple machines, or re-installed (rather than regenerated) after a clean install.3. postinst scripts need to run in a non-interactive context which makes prompting the user difficult (or requires you to abuse debconf). gdp scripts can expect an interactive terminal for prompting.4. download requirements in gdp can be much more complex than you may be comfortable implementing in a postinst script: multiple mirrors, mirror selection, parallel downloads, retries, user-supplied local copies of files to download, proxy specification, etc.5. common needs between packages (e.g. download logic, patch logic, etc.) can be in shared routines.6. other non-live stuff can be shared (icons, package descriptions, etc.) in some cases (e.g. variants of the same game such as the Doom family)7. the .deb files that gdp generates have a correct Installed-Size.