Right now, the ability to move artifacts is linked to the ability to delete (because technically it's a delete + create). With recent improvement on move (more complete) this limiation no longer makes sense and should be lifted.
However is some situation, it might be critical to guarranty that no artifacts created in a given Tracker got removed (hence moved). In order to keep this behaviour, a new parameter is introduced at tracker level to enable/disable the ability to move. Move is enabled by default on all trackers.