I do like the idea of involving Grand Companies, linkshells, and possibly free companies(?) in with hamlet defenses. Certain LS's could claim certain areas as their own, make their own guild halls, housing, etc., and possibly even compete or cooperate with other LS's to prosper. Just imagine: two different hamlets/LS's could exchange goods and services between each other, or even build up armies of airships, Magitek armor, and various mounts to take siege of the other's areas for total domination. Then, some other force, such as the Garlean Empire and/or beastmen tribes show up and take it for themselves, and then everyone has to cooperate together to drive them back out... I dunno about you, but Final Fantasy or not, that sounds pretty damn fun to me.
It keeps players working towards a common goal, allows for cooperation or competition, makes crafting and gathering jobs more viable, AND it always keeps everyone in suspense because you never know what's going to happen next. And if that doesn't appeal to you... well, you can still do leves, quests, and all the other stuff that's still in the game. I see nothing wrong with it, other than the fact that it's not in the game yet.
