The pack system was designed to work without a central authority. Using a URL pattern to fetch a new version allows for that. The price is indeed that you cannot migrate to another server. The central database that keep track of packs being downloaded can do so, but after some issues the rules were tightened not to allow registering a new version from a different location as well.
I think the current pack system is a bit too simple. It did prove the need for one and I guess it is time for some redesign …