The terminator robot becoming such a "catchy" representation is due, I believe, to the fact that our minds and the fears they dream up are embodied. We have evolved to fear moving atoms: tigers that could attack us, tornados that could ruin our shelters, waves that could drown us, human opponents that could harm us. Killer robots from the future are just a spinoff that cultural evolution has put onto our deeply rooted sources of fear that we've evolved to react to. Just because silent and stealthy taking over by AI does not give us the heebie-jeebies quite as much as roaring armies of terminators do, that doesn't mean it is not equally dangerous or even more so.
