This has been discussed so many times on the forum, and it's how the sim works.
Addons installed using the new suggested installation system, cannot be moved. The CAN be disabled, but from the "Options->Addons" menu.
While it might be nice the new system allowed to rearrange areas with the sim UI (the system DOES support layer priorities, it's just a matter of the UI not allowing changes), we think the advantage of this method are too many to not use it. And, eventually, an update of the sim might allow to rearrange even these areas, if enough users would ask LM to add that feature.
