In the open-source package managers I studied, there is typically a distinction between the person who develops a package (the developer) and the person who adds it to the package manager. (the packager) In package managers like Apple’s App Store, the developer and packager are the same person. This may go a long way to explaining the differences observed in long descriptions.
The incentives for the packager are different in the two situations. When the packager and developer are the same, the packager’s motivation is generally to get as many downloads as possible, even if it degrades the quality of the repository. (Tragedy of the Commons) There is little-to-no incentive to avoid users inadvertently downloading the package even if it is not relevant to the user’s interests.
On the other hand, when the packager and developer are separate, the packager’s incentive is to maximise the quality of the repository by making additional packages available and making it easy for users to find the package, if they want it, and to skip over it if it is not what they want. In addition, each package added to a repository requires some effort on the part of the packager. This provides an incentive to only add packages that are likely to be useful to the community.
This difference may go a long way to explaining the difference in the style and usefulness of the long descriptions in the open-source package managers versus Apple’s App Store. There is also evidence that packages in the package managers with a separation between packager and developer are installed more frequently.
As pointed out by AppsFire, 80% of packages in Apple’s App Store are not being used, and even the 1000th most popular package is installed by only 1.76% of users. (data from October 2009) This is likely a result of both weaknesses in the discovery process (discussed here, here, here, here, here, here, and here.), and a glut of so-called “fart apps” that provide very little to the App Store aside from inflating it’s statistics.
Comparing to data for Ubuntu, the top 5600 packages are installed by the same percentage of users, and almost all packages are installed by at least one user, with a much shorter long tail – 51% of packages are installed by at least 1% of users. This can be partially attributed to better performance by users in finding the packages they need. The burden on package managers also likely serves as a filter, keeping out the “fart apps.”
Although the model used by the open-source package managers is unlikely to be adopted by Apple, it produces a repository that is both more usable and has contents that are, on average, more desirable to the users.