I think village defenses go much more smoothly if large numbers of a particular clan/faction sign up together. That way, while the whole team may not be working on the same wave-length, at least little clumps of clanmates will be coordinating.
An official TS/Vent channel server thingy would be helpful for those wishing to organize village defenses, though I might point out that organization is difficult without any sort of chain of command, even if that chain is composed of only two links (one leader, and the mass of 'the lead').
Perhaps somebody--an admin, a dev, or (even better) a person chosen just prior to the battle by popular consent, could be appointed as the A.I. defense's official leader. If defenders got into the habit of doing this, the defense of A.I. shit would be much more coordinated.