I hate to think of a FF world that lack giant critter's didn't pop up from time to time. There is some awesome about being along traveling threw a zone and than sudden a 500 ton Wrym appears. Don't get me wrong "I don't want old world HNM's."
Perhaps some new system could be place in like a quest. Where you would talk to a npc in town. And than some where random in a zone your monster would pop. Alliance's flag for the quest could than all branch out searching for it. And only those player's that are flag could lay claim to it.
IDK if the whole searching thing would bring back the nostalgia of the HNM hunt. But the idea behind this would allow all players to get a chance at loot and drops. And add a bit of adventure by searching the mob out.