The loot is stronger there to create more pvp if you're on a populated server it's very rare to find it unguarded by another player... but if you're playing on low pop night servers... Well then that's different... The military bases are the last stands so therefore it's suppose to have high loot count. Eventually Rocket already said he is wanting to add a heavy amount of zombies but you have to take in account how much loot, vehicles, players, and NPC's there are so slowly they will be adding zombies in as well as smaller hordes that roam apparently.