It would be nice if each alliance had an inactivity timer that they could set to some extent and that people could know when joining. For example, my alliance has a policy of kicking people who have not played for five days. If we could make that a setting on the alliance itself, people will know that before they join.
As an added benefit, those rules could apply to the alliance leader and help keep teams alive that would otherwise die on the vine due to an inactive leader, but that's an idea for another suggestion...