That's a problem in a lot of horror stories that attempt to follow Lovecraft's "Cthulhu Mythos". They turn Cthulhu and rest of the Old Ones into evil demons who want to harm humanity. That makes them less interesting. The idea of cosmic horror is that these powerful beings simply don't care about humanity. Yes, if they return humanity will suffer, but that isn't their goal. And that is truly scary -- that we don't matter to the beings in power.
