I don't understand why mobs randomly attack player structures. I mean, usually they don't. Usually, they aggro player stuff only if they aggro the player. If they can't get to you, they attack buildings etc, even stuff the player didn't build.

I have bases all over, and most of the time, none of it gets attacked when I'm not there. Then one day I'm getting back to a meadows base at the edge of the swamp, and there's an abomination leveling the whole place for no reason.