What I am asking for is the ability to disable add-ons without having to
delete or manually move them. When many add-ons are installed (especially
WML-heavy add-ons), it takes way to long to start a multiplayer game. Also,
add-ons can sometimes conflict with one another.

Simply deleting add-ons is not always a viable solution because the player
migt have a slow Internet connection and may want to play the add-on again
in the future.

One way this could be implemented is by temporarily moving disabled add-ons
to a different folder.