Not only is this unreasonable, it seems to be pretty much impossible. Very few manufacturers of anything are held responsible for the bad things that happen when the things they make are used.
* Cars
* Guns
* Knives
* Drugs
* Food
And when your dalek kills someone, whose fault is it? Is it the hardware manufacturer's fault? Or the software writer's? Which of those writers? What if we can narrow it down to some component - maybe it's that component manufacturer's fault, not DalekCo's. Or maybe the steel/plastic/pudding that went into that component was a bad batch. Or maybe the dalek watched too many Tom & Jerry's cartoons. Chuck Jones is at fault because he portrayed cartoon characters that could survive being hit over the head with a frying pan. It was not the Dalek's fault - blame the dead guy. Because that's what happens - you blame the dead guy.
I'm not saying that nobody is ever responsible. I'm just saying that it is sometimes the case that assigning the blame can be impossible, and it can also be worthless.