We now have robots that can decide to kill. Do we really want those? See what happened when you had drones shoot missiles at people? A lot of weddings got bombed.
ya, i want them. all things being equal, computers make fewer mistakes than humans. also, the algorithms of a computer can be tested, evaluated and approved (or denied).
if you are going to make the "well computers can be coded to bad things" argument, then i'd say well, humans can be (easily) persuaded to do bad things. it ultimately depends on the agent pulling the proverbial strings, not whether the puppet is made of meat or electronics.