True, for many uses it would be cleaner to write application data to the bundle, even though this isn't commonly writeable. As someone who develops professiona

True, for many uses it would be cleaner to write application data to the bundle, even though this isn't commonly writeable. As someone who develops professional apps for Mac, I can thin of a few circumstances where this definitely won't work, or at least will introduce other compromises or require a whole lot of extra effort of developers and/or users. - You want to uninstall/re-install an app without removing the application's data - The application's data can become large (think raw audio or video libraries) and users request to store it in a separate disk - Users want to personally organize the data they make with your app (by project, client, personal/work, etc.), or use it with other apps - Your "installer" is just a zip of the .app bundle and there is no obvious opportunity to assume admin privileges make the bundle writeable Most of these could be solved by having a separate "sandbox" a la iOS or MAS that can be moved or, at the user's option, remain on disk when uninstalling; as far as I know neither system offers these capabilities.