Let's say you needed a workforce that you wanted to work on the cheap. So, you import a contingent of robots into your country. All is well for a few decades, but now the majority of the robots don't want to work anymore. Instead, they live off government funds, replicate themselves without restraint, congregate in bad robot neigborhoods, and murder people at random.
Now, what would you do about these bad robots? Let them wander around killing people at random? Pissh! Of course not! You would destroy them, would you not? It just stands to reason.