Sometimes I wonder of people have ever been into the Construction Set for Morrowind, and seen all the Ninja-Monkeys everywhere. Even if they didn't, they should have at least started to wonder where all the Ash Zombies went, and why there are Ascended Sleepers all over Red Mountain.
Maybe it's because many interiors don't respawn, so people have a tendency to assume the inhabitants are set, as they aren't as obviously exposed to the leveling in an area...