I would rather the game spawn the quests, and monsters/lairs in stages. let the world start out with weaker monsters, then at the mid-game, new lairs are discovered and spawn across the non-settled areas of the map. Finally, at a third stage, many ancient and powerful denizens will awaken.
I would also like to see "Evil Champions" who are killed respawn during stage 3 as zombies of some kind.
The second wave would trigger new monsters to spawn at each lair, changing each lair to +1 stronger monsters. Then each monster still in the world gets several buffs and new ones begin to appear.
This would be more "sane" than having a big blotch of monsters of all shapes and sizes on earth. Remember fall from heaven? The Armageddon Counter could be used (or something akin) to determine how close the world is to breaking apart. Thus a new purpose in Elemental is to repair the land - Kingdoms and Empires both want to keep the land itself together, and that would be like another way to end the game.
I have always felt the best way to approach this is to have more rabbit hole dungeons, and quests/events that regulate the ebb of the monster tide. One event i would like to see, is Every "wild shard" (mana crystal outside of borders) begin spawning elementals as though the monster AI had just got binding. In fact, let "Dark Shrine" rabbit holes appear on them for monsters to spawn at and players to "cleanse" or "blight".