Want something to be scared of? Be scared of the thousands of small networked bots armed with a small, compact 9mm pistol who are barely larger than the weapon they're carrying, and can hide nearly anywhere.
Or helicopter drones. Once you take a human out of the equation for a helicopter they're surprisingly agile.
Exactly! We want to create a robot in our image, but legs are really very inefficient, especially if armor is required. Small bots (flying or otherwise) are a much better use of resources and much harder to find and destroy.
Now, giant armored tank-based robots on treads... Yeah, that might work.